使用动态 header 大小的 UICollectionView 时出现 UIViewAlertForUnsatisfiableConstraints 错误
UIViewAlertForUnsatisfiableConstraints errors when working with dynamic header size UICollectionView
简介
我正在尝试为我的 collectionView 的 header 单元格设置动态单元格大小。用作 header 的单元格也用作另一个 collectionView 中的“常规”单元格。在那里，使用动态单元格大小调整工作得很好。
collectionView 是这样创建的：
private lazy var timelineCollectionView: UICollectionView = {
let flowLayout = UICollectionViewFlowLayout()
flowLayout.scrollDirection = .vertical
flowLayout.estimatedItemSize = CGSize(width: self.view.frame.width, height: 10)
flowLayout.minimumInteritemSpacing = 0
flowLayout.minimumLineSpacing = 0
let cv = UICollectionView(frame: .zero, collectionViewLayout: flowLayout)
cv.alwaysBounceVertical = true
cv.contentInsetAdjustmentBehavior = .never
cv.backgroundColor = .clear
cv.scrollIndicatorInsets = UIEdgeInsets(top: self.coloredTitleBarHeight - self.getStatusBarHeight(), left: 0, bottom: 0, right: 0)
cv.delegate = self
cv.dataSource = self
cv.register(TLContentCell.self, forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader, withReuseIdentifier: "content-header-cell")
return cv
}()
我已经按照 this tutorial 使用动态单元格高度。
按照教程，这是我单元格中的代码片段：
private lazy var width: NSLayoutConstraint = {
let width = contentView.widthAnchor.constraint(equalToConstant: bounds.size.width)
width.isActive = true
return width
}()
override init(frame: CGRect) {
super.init(frame: frame)
contentView.translatesAutoresizingMaskIntoConstraints = false
contentView.backgroundColor = UIColor.white
}
override func systemLayoutSizeFitting(_ targetSize: CGSize, withHorizontalFittingPriority horizontalFittingPriority: UILayoutPriority, verticalFittingPriority: UILayoutPriority) -> CGSize {
width.constant = bounds.size.width
return contentView.systemLayoutSizeFitting(CGSize(width: targetSize.width, height: 1))
}
func setupViews() {
// view setup happens here
if let lastSubview = contentView.subviews.last {
contentView.bottomAnchor.constraint(equalTo: lastSubview.bottomAnchor, constant: 0).isActive = true
}
}
同样，如果我将单元格用作常规单元格，而不是在 header 或 collectionView 的页脚中，此代码完全可以正常工作。
现在，我只是想在 header 中使用它。由于无法为 header 单元格提供类似 estimatedItemSize 的内容，因此我使用了以下方法，可在 this SO post:
中找到
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
let indexPath = IndexPath(row: 0, section: section)
let headerView = self.collectionView(collectionView, viewForSupplementaryElementOfKind: UICollectionView.elementKindSectionHeader, at: indexPath) as! TLContentCell
headerView.layoutIfNeeded()
return headerView.systemLayoutSizeFitting(CGSize(width: collectionView.frame.width, height: UIView.layoutFittingExpandedSize.height),
withHorizontalFittingPriority: .required, // Width is fixed
verticalFittingPriority: .fittingSizeLevel) // Height can be as large as needed
}
事实上，header 单元格调整大小正确。 然而，UIKit 打印看似无穷无尽的 UIViewAlertForUnsatisfiableConstraints 错误（由于 SO 字符限制而缩短）：
2020-01-16 15:29:00.427001+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x600000024820 MyApp.DefaultLabel:0x7fa6fc579090'3d'.width == 17.6667 (active)>",
"<NSLayoutConstraint:0x600000024780 MyApp.AnimatedButton:0x7fa6fc5786d0.width == 20 (active)>",
"<NSLayoutConstraint:0x6000000245f0 UIImageView:0x7fa6fc578020.width == 45 (active)>",
"<NSLayoutConstraint:0x600000024550 H:|-(0)-[UIImageView:0x7fa6fc578020](LTR) (active, names: '|':UIView:0x7fa6fc578980 )>",
"<NSLayoutConstraint:0x600000024730 MyApp.AnimatedButton:0x7fa6fc5786d0.right == UIView:0x7fa6fc578980.right (active)>",
"<NSLayoutConstraint:0x6000000247d0 MyApp.DefaultLabel:0x7fa6fc579090'3d'.right == MyApp.AnimatedButton:0x7fa6fc5786d0.left - 4 (active)>",
"<NSLayoutConstraint:0x600000024a50 H:[UIImageView:0x7fa6fc578020]-(8)-[MyApp.DefaultLabel:0x7fa6fc578460'@unitedholograms'](LTR) (active)>",
"<NSLayoutConstraint:0x600000024910 MyApp.DefaultLabel:0x7fa6fc578460'@unitedholograms'.right == MyApp.DefaultLabel:0x7fa6fc579090'3d'.left (active)>",
"<NSLayoutConstraint:0x600000024be0 H:|-(16)-[UIView:0x7fa6fc578980](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x600000024c30 UIView:0x7fa6fc578980.right == UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x6000000245f0 UIImageView:0x7fa6fc578020.width == 45 (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2020-01-16 15:29:00.427892+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x6000000252c0 UIStackView:0x7fa6fc57a470.width == 80 (active)>",
"<NSLayoutConstraint:0x600000024fa0 H:|-(0)-[UIImageView:0x7fa6fc57a610](LTR) (active, names: '|':UIView:0x7fa6fc57a300 )>",
"<NSLayoutConstraint:0x600000025040 UIImageView:0x7fa6fc57a610.right == UIStackView:0x7fa6fc57a470.left - 8 (active)>",
"<NSLayoutConstraint:0x600000025220 UIStackView:0x7fa6fc57a470.right == UIView:0x7fa6fc57a300.right (active)>",
"<NSLayoutConstraint:0x600000025360 H:|-(0)-[UIView:0x7fa6fc57a300](LTR) (active, names: '|':UIView:0x7fa6fc57a010 )>",
"<NSLayoutConstraint:0x6000000253b0 UIView:0x7fa6fc57a300.right == UIView:0x7fa6fc57a010.right (active)>",
"<NSLayoutConstraint:0x600000025590 H:|-(16)-[UIView:0x7fa6fc57a010](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x6000000255e0 UIView:0x7fa6fc57a010.right == UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x6000000252c0 UIStackView:0x7fa6fc57a470.width == 80 (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2020-01-16 15:29:00.428596+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x600000024820 MyApp.DefaultLabel:0x7fa6fc579090'3d'.width == 17.6667 (active)>",
"<NSLayoutConstraint:0x600000024780 MyApp.AnimatedButton:0x7fa6fc5786d0.width == 20 (active)>",
"<NSLayoutConstraint:0x600000024550 H:|-(0)-[UIImageView:0x7fa6fc578020](LTR) (active, names: '|':UIView:0x7fa6fc578980 )>",
"<NSLayoutConstraint:0x600000024730 MyApp.AnimatedButton:0x7fa6fc5786d0.right == UIView:0x7fa6fc578980.right (active)>",
"<NSLayoutConstraint:0x6000000247d0 MyApp.DefaultLabel:0x7fa6fc579090'3d'.right == MyApp.AnimatedButton:0x7fa6fc5786d0.left - 4 (active)>",
"<NSLayoutConstraint:0x600000024a50 H:[UIImageView:0x7fa6fc578020]-(8)-[MyApp.DefaultLabel:0x7fa6fc578460'@unitedholograms'](LTR) (active)>",
"<NSLayoutConstraint:0x600000024910 MyApp.DefaultLabel:0x7fa6fc578460'@unitedholograms'.right == MyApp.DefaultLabel:0x7fa6fc579090'3d'.left (active)>",
"<NSLayoutConstraint:0x600000024be0 H:|-(16)-[UIView:0x7fa6fc578980](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x600000024c30 UIView:0x7fa6fc578980.right == UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x600000024780 MyApp.AnimatedButton:0x7fa6fc5786d0.width == 20 (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2020-01-16 15:29:00.429543+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x600000024820 MyApp.DefaultLabel:0x7fa6fc579090'3d'.width == 17.6667 (active)>",
"<NSLayoutConstraint:0x600000024550 H:|-(0)-[UIImageView:0x7fa6fc578020](LTR) (active, names: '|':UIView:0x7fa6fc578980 )>",
"<NSLayoutConstraint:0x600000024730 MyApp.AnimatedButton:0x7fa6fc5786d0.right == UIView:0x7fa6fc578980.right (active)>",
"<NSLayoutConstraint:0x6000000247d0 MyApp.DefaultLabel:0x7fa6fc579090'3d'.right == MyApp.AnimatedButton:0x7fa6fc5786d0.left - 4 (active)>",
"<NSLayoutConstraint:0x600000024a50 H:[UIImageView:0x7fa6fc578020]-(8)-[MyApp.DefaultLabel:0x7fa6fc578460'@unitedholograms'](LTR) (active)>",
"<NSLayoutConstraint:0x600000024910 MyApp.DefaultLabel:0x7fa6fc578460'@unitedholograms'.right == MyApp.DefaultLabel:0x7fa6fc579090'3d'.left (active)>",
"<NSLayoutConstraint:0x600000024be0 H:|-(16)-[UIView:0x7fa6fc578980](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x600000024c30 UIView:0x7fa6fc578980.right == UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x600000024820 MyApp.DefaultLabel:0x7fa6fc579090'3d'.width == 17.6667 (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2020-01-16 15:29:00.430324+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x6000000250e0 V:|-(0)-[UIStackView:0x7fa6fc57a470] (active, names: '|':UIView:0x7fa6fc57a300 )>",
"<NSLayoutConstraint:0x600000025090 UIStackView:0x7fa6fc57a470.bottom == UIView:0x7fa6fc57a300.bottom (active)>",
"<NSLayoutConstraint:0x600000025400 UIView:0x7fa6fc57a300.height == 0.5625*UIView:0x7fa6fc57a300.width (active)>",
"<NSLayoutConstraint:0x600000025360 H:|-(0)-[UIView:0x7fa6fc57a300](LTR) (active, names: '|':UIView:0x7fa6fc57a010 )>",
"<NSLayoutConstraint:0x6000000253b0 UIView:0x7fa6fc57a300.right == UIView:0x7fa6fc57a010.right (active)>",
"<NSLayoutConstraint:0x600000025590 H:|-(16)-[UIView:0x7fa6fc57a010](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x6000000255e0 UIView:0x7fa6fc57a010.right == UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>",
"<NSLayoutConstraint:0x600000026210 'UISV-canvas-connection' UIStackView:0x7fa6fc57a470.top == UIImageView:0x7fa6fc57a7e0.top (active)>",
"<NSLayoutConstraint:0x600000026260 'UISV-canvas-connection' V:[UIImageView:0x7fa6fc57ab80]-(0)-| (active, names: '|':UIStackView:0x7fa6fc57a470 )>",
"<NSLayoutConstraint:0x600000026300 'UISV-fill-equally' UIImageView:0x7fa6fc57a9b0.height == UIImageView:0x7fa6fc57a7e0.height (active)>",
"<NSLayoutConstraint:0x6000000263a0 'UISV-fill-equally' UIImageView:0x7fa6fc57ab80.height == UIImageView:0x7fa6fc57a7e0.height (active)>",
"<NSLayoutConstraint:0x6000000262b0 'UISV-spacing' V:[UIImageView:0x7fa6fc57a7e0]-(8)-[UIImageView:0x7fa6fc57a9b0] (active)>",
"<NSLayoutConstraint:0x600000026350 'UISV-spacing' V:[UIImageView:0x7fa6fc57a9b0]-(8)-[UIImageView:0x7fa6fc57ab80] (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x600000026350 'UISV-spacing' V:[UIImageView:0x7fa6fc57a9b0]-(8)-[UIImageView:0x7fa6fc57ab80] (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2020-01-16 15:29:00.431297+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x60000003df90 UIImageView:0x7fa6fc576970.width == 13 (active)>",
"<NSLayoutConstraint:0x60000003e030 H:|-(4)-[UIImageView:0x7fa6fc576970](LTR) (active, names: '|':UIView:0x7fa6fc56e2d0 )>",
"<NSLayoutConstraint:0x60000003e940 H:[UIImageView:0x7fa6fc576970]-(4)-[MyApp.DefaultLabel:0x7fa6fc576700'by linus_hologram '](LTR) (active)>",
"<NSLayoutConstraint:0x60000003e440 MyApp.DefaultLabel:0x7fa6fc576700'by linus_hologram '.right == UIView:0x7fa6fc56e2d0.right - 4 (active)>",
"<NSLayoutConstraint:0x6000000e2bc0 H:|-(16)-[UIView:0x7fa6fc56e2d0](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x600000023930 UIView:0x7fa6fc56e2d0.right <= UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x600000025ae0 MyApp.DefaultLabel:0x7fa6fc575060'0'.right == UIView:0x7fa6fc57c3e0.right (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2020-01-16 15:29:00.434486+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x60000003e030 H:|-(4)-[UIImageView:0x7fa6fc576970](LTR) (active, names: '|':UIView:0x7fa6fc56e2d0 )>",
"<NSLayoutConstraint:0x60000003e940 H:[UIImageView:0x7fa6fc576970]-(4)-[MyApp.DefaultLabel:0x7fa6fc576700'by linus_hologram '](LTR) (active)>",
"<NSLayoutConstraint:0x60000003e440 MyApp.DefaultLabel:0x7fa6fc576700'by linus_hologram '.right == UIView:0x7fa6fc56e2d0.right - 4 (active)>",
"<NSLayoutConstraint:0x6000000e2bc0 H:|-(16)-[UIView:0x7fa6fc56e2d0](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x600000023930 UIView:0x7fa6fc56e2d0.right <= UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x60000003e940 H:[UIImageView:0x7fa6fc576970]-(4)-[MyApp.DefaultLabel:0x7fa6fc576700'by linus_hologram '](LTR) (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2020-01-16 15:29:00.435062+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x600000024550 H:|-(0)-[UIImageView:0x7fa6fc578020](LTR) (active, names: '|':UIView:0x7fa6fc578980 )>",
"<NSLayoutConstraint:0x600000024730 MyApp.AnimatedButton:0x7fa6fc5786d0.right == UIView:0x7fa6fc578980.right (active)>",
"<NSLayoutConstraint:0x6000000247d0 MyApp.DefaultLabel:0x7fa6fc579090'3d'.right == MyApp.AnimatedButton:0x7fa6fc5786d0.left - 4 (active)>",
"<NSLayoutConstraint:0x600000024a50 H:[UIImageView:0x7fa6fc578020]-(8)-[MyApp.DefaultLabel:0x7fa6fc578460'@unitedholograms'](LTR) (active)>",
"<NSLayoutConstraint:0x600000024910 MyApp.DefaultLabel:0x7fa6fc578460'@unitedholograms'.right == MyApp.DefaultLabel:0x7fa6fc579090'3d'.left (active)>",
"<NSLayoutConstraint:0x600000024be0 H:|-(16)-[UIView:0x7fa6fc578980](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x600000024c30 UIView:0x7fa6fc578980.right == UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x600000024a50 H:[UIImageView:0x7fa6fc578020]-(8)-[MyApp.DefaultLabel:0x7fa6fc578460'@unitedholograms'](LTR) (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2020-01-16 15:29:00.435727+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x600000024550 H:|-(0)-[UIImageView:0x7fa6fc578020](LTR) (active, names: '|':UIView:0x7fa6fc578980 )>",
"<NSLayoutConstraint:0x600000024730 MyApp.AnimatedButton:0x7fa6fc5786d0.right == UIView:0x7fa6fc578980.right (active)>",
"<NSLayoutConstraint:0x6000000247d0 MyApp.DefaultLabel:0x7fa6fc579090'3d'.right == MyApp.AnimatedButton:0x7fa6fc5786d0.left - 4 (active)>",
"<NSLayoutConstraint:0x600000024960 H:[UIImageView:0x7fa6fc578020]-(8)-[MyApp.DefaultLabel:0x7fa6fc5781f0'MyApp'](LTR) (active)>",
"<NSLayoutConstraint:0x6000000249b0 MyApp.DefaultLabel:0x7fa6fc5781f0'MyApp'.right == MyApp.DefaultLabel:0x7fa6fc579090'3d'.left (active)>",
"<NSLayoutConstraint:0x600000024be0 H:|-(16)-[UIView:0x7fa6fc578980](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x600000024c30 UIView:0x7fa6fc578980.right == UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x600000024960 H:[UIImageView:0x7fa6fc578020]-(8)-[MyApp.DefaultLabel:0x7fa6fc5781f0'MyApp'](LTR) (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2020-01-16 15:29:00.436212+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x600000024fa0 H:|-(0)-[UIImageView:0x7fa6fc57a610](LTR) (active, names: '|':UIView:0x7fa6fc57a300 )>",
"<NSLayoutConstraint:0x600000025040 UIImageView:0x7fa6fc57a610.right == UIStackView:0x7fa6fc57a470.left - 8 (active)>",
"<NSLayoutConstraint:0x600000025220 UIStackView:0x7fa6fc57a470.right == UIView:0x7fa6fc57a300.right (active)>",
"<NSLayoutConstraint:0x600000025360 H:|-(0)-[UIView:0x7fa6fc57a300](LTR) (active, names: '|':UIView:0x7fa6fc57a010 )>",
"<NSLayoutConstraint:0x6000000253b0 UIView:0x7fa6fc57a300.right == UIView:0x7fa6fc57a010.right (active)>",
"<NSLayoutConstraint:0x600000025590 H:|-(16)-[UIView:0x7fa6fc57a010](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x6000000255e0 UIView:0x7fa6fc57a010.right == UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x600000025220 UIStackView:0x7fa6fc57a470.right == UIView:0x7fa6fc57a300.right (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2020-01-16 15:29:00.436954+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x600000025680 H:|-(0)-[MyApp.PostInteractionButton:0x7fa6fc5720f0](LTR) (active, names: '|':UIView:0x7fa6fc579e80 )>",
"<NSLayoutConstraint:0x600000025720 MyApp.PostInteractionButton:0x7fa6fc5720f0.right == MyApp.DefaultLabel:0x7fa6fc573090'1'.left - 8 (active)>",
"<NSLayoutConstraint:0x600000025810 MyApp.DefaultLabel:0x7fa6fc573090'1'.right == UIView:0x7fa6fc579e80.right (active)>",
"<NSLayoutConstraint:0x600000025ef0 H:|-(16)-[UIStackView:0x7fa6fc579cf0](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x600000025540 UIStackView:0x7fa6fc579cf0.right == UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>",
"<NSLayoutConstraint:0x6000000265d0 'UISV-canvas-connection' UIStackView:0x7fa6fc579cf0.leading == UIView:0x7fa6fc579e80.leading (active)>",
"<NSLayoutConstraint:0x600000026620 'UISV-canvas-connection' H:[MyApp.PostInteractionButton:0x7fa6fc5752d0]-(0)-| (active, names: '|':UIStackView:0x7fa6fc579cf0 )>",
"<NSLayoutConstraint:0x6000000266c0 'UISV-distributing-edge' H:[UIView:0x7fa6fc579e80]-(0)-[_UIOLAGapGuide:0x600001f8cd00'UISV-distributing'] (active)>",
"<NSLayoutConstraint:0x600000026710 'UISV-distributing-edge' _UIOLAGapGuide:0x600001f8cd00'UISV-distributing'.trailing == UIView:0x7fa6fc57c3e0.leading (active)>",
"<NSLayoutConstraint:0x600000026800 'UISV-distributing-edge' H:[UIView:0x7fa6fc57c3e0]-(0)-[_UIOLAGapGuide:0x600001f8d300'UISV-distributing'] (active)>",
"<NSLayoutConstraint:0x600000026850 'UISV-distributing-edge' _UIOLAGapGuide:0x600001f8d300'UISV-distributing'.trailing == UIView:0x7fa6fc57c6d0.leading (active)>",
"<NSLayoutConstraint:0x6000000267b0 'UISV-distributing-edge' H:[UIView:0x7fa6fc57c6d0]-(0)-[_UIOLAGapGuide:0x600001f8d400'UISV-distributing'] (active)>",
"<NSLayoutConstraint:0x600000026940 'UISV-distributing-edge' _UIOLAGapGuide:0x600001f8d400'UISV-distributing'.trailing == MyApp.PostInteractionButton:0x7fa6fc5752d0.leading (active)>",
"<NSLayoutConstraint:0x6000000268a0 'UISV-fill-equally' _UIOLAGapGuide:0x600001f8d300'UISV-distributing'.width == _UIOLAGapGuide:0x600001f8cd00'UISV-distributing'.width (active)>",
"<NSLayoutConstraint:0x600000026990 'UISV-fill-equally' _UIOLAGapGuide:0x600001f8d400'UISV-distributing'.width == _UIOLAGapGuide:0x600001f8cd00'UISV-distributing'.width (active)>"
)
结尾
我真的不知道为什么会有这种行为。特别是如果我不将该单元格用作 header 单元格，一切都运行良好。
我们可以将这些错误插入 WTF Auto Layout? 并更好地了解正在发生的事情。
让我们从first one开始。最后 3 行在这里很有趣：
- View1 的前缘应等于 View2 的前缘加 16。
- View1 的后缘应等于 View2 的后缘减去 16。
- View2 的宽度应等于 0。
但是，看起来打破约束的是设置为 45 的图像视图的宽度。UIImageView:0x7fa6fc578020.width == 45
还有另一个约束将 imageView 和 View1 配对在一起：ImageView's leading edge should equal View1's leading edge.
有了这些细节，我们就可以开始构想它的布局了。
View2LeadingEdge - 16pts - View1LeadingEdge - ImageViewLeading - 45pts - ImageViewTrailing - View1TrailingEdge - 16pts - View2Trailing
对我来说，View2 的宽度为零似乎有些不对劲。请注意错误中的每组破坏约束，您会看到如下一行：
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>"
我想我需要更多的上下文来完成调试，但这应该能让您顺利开始。我不确定 View2 到底是什么，但我会尝试弄清楚为什么它的宽度设置为零。
您似乎并没有忘记禁用 translatesAutoResizingMask 或单元格自动添加此约束以强制布局，因此如果您无法弄清楚，您也可以尝试将优先级设置为 View1's trailing edge should equal View2's trailing edge minus 16. 到 .defaultHigh 以查看是否可以帮助自动布局引擎确定最佳布局。
也不要忘记检查此设置：
(
"<NSLayoutConstraint:0x600000025680 H:|-(0)-[MyApp.PostInteractionButton:0x7fa6fc5720f0](LTR) (active, names: '|':UIView:0x7fa6fc579e80 )>",
"<NSLayoutConstraint:0x600000025720 MyApp.PostInteractionButton:0x7fa6fc5720f0.right == MyApp.DefaultLabel:0x7fa6fc573090'1'.left - 8 (active)>",
"<NSLayoutConstraint:0x600000025810 MyApp.DefaultLabel:0x7fa6fc573090'1'.right == UIView:0x7fa6fc579e80.right (active)>",
"<NSLayoutConstraint:0x600000025ef0 H:|-(16)-[UIStackView:0x7fa6fc579cf0](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x600000025540 UIStackView:0x7fa6fc579cf0.right == UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>",
"<NSLayoutConstraint:0x6000000265d0 'UISV-canvas-connection' UIStackView:0x7fa6fc579cf0.leading == UIView:0x7fa6fc579e80.leading (active)>",
"<NSLayoutConstraint:0x600000026620 'UISV-canvas-connection' H:[MyApp.PostInteractionButton:0x7fa6fc5752d0]-(0)-| (active, names: '|':UIStackView:0x7fa6fc579cf0 )>",
"<NSLayoutConstraint:0x6000000266c0 'UISV-distributing-edge' H:[UIView:0x7fa6fc579e80]-(0)-[_UIOLAGapGuide:0x600001f8cd00'UISV-distributing'] (active)>",
"<NSLayoutConstraint:0x600000026710 'UISV-distributing-edge' _UIOLAGapGuide:0x600001f8cd00'UISV-distributing'.trailing == UIView:0x7fa6fc57c3e0.leading (active)>",
"<NSLayoutConstraint:0x600000026800 'UISV-distributing-edge' H:[UIView:0x7fa6fc57c3e0]-(0)-[_UIOLAGapGuide:0x600001f8d300'UISV-distributing'] (active)>",
"<NSLayoutConstraint:0x600000026850 'UISV-distributing-edge' _UIOLAGapGuide:0x600001f8d300'UISV-distributing'.trailing == UIView:0x7fa6fc57c6d0.leading (active)>",
"<NSLayoutConstraint:0x6000000267b0 'UISV-distributing-edge' H:[UIView:0x7fa6fc57c6d0]-(0)-[_UIOLAGapGuide:0x600001f8d400'UISV-distributing'] (active)>",
"<NSLayoutConstraint:0x600000026940 'UISV-distributing-edge' _UIOLAGapGuide:0x600001f8d400'UISV-distributing'.trailing == MyApp.PostInteractionButton:0x7fa6fc5752d0.leading (active)>",
"<NSLayoutConstraint:0x6000000268a0 'UISV-fill-equally' _UIOLAGapGuide:0x600001f8d300'UISV-distributing'.width == _UIOLAGapGuide:0x600001f8cd00'UISV-distributing'.width (active)>",
"<NSLayoutConstraint:0x600000026990 'UISV-fill-equally' _UIOLAGapGuide:0x600001f8d400'UISV-distributing'.width == _UIOLAGapGuide:0x600001f8cd00'UISV-distributing'.width (active)>"
)
简介
我正在尝试为我的 collectionView 的 header 单元格设置动态单元格大小。用作 header 的单元格也用作另一个 collectionView 中的“常规”单元格。在那里，使用动态单元格大小调整工作得很好。
collectionView 是这样创建的：
private lazy var timelineCollectionView: UICollectionView = {
let flowLayout = UICollectionViewFlowLayout()
flowLayout.scrollDirection = .vertical
flowLayout.estimatedItemSize = CGSize(width: self.view.frame.width, height: 10)
flowLayout.minimumInteritemSpacing = 0
flowLayout.minimumLineSpacing = 0
let cv = UICollectionView(frame: .zero, collectionViewLayout: flowLayout)
cv.alwaysBounceVertical = true
cv.contentInsetAdjustmentBehavior = .never
cv.backgroundColor = .clear
cv.scrollIndicatorInsets = UIEdgeInsets(top: self.coloredTitleBarHeight - self.getStatusBarHeight(), left: 0, bottom: 0, right: 0)
cv.delegate = self
cv.dataSource = self
cv.register(TLContentCell.self, forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader, withReuseIdentifier: "content-header-cell")
return cv
}()
我已经按照 this tutorial 使用动态单元格高度。
按照教程，这是我单元格中的代码片段：
private lazy var width: NSLayoutConstraint = {
let width = contentView.widthAnchor.constraint(equalToConstant: bounds.size.width)
width.isActive = true
return width
}()
override init(frame: CGRect) {
super.init(frame: frame)
contentView.translatesAutoresizingMaskIntoConstraints = false
contentView.backgroundColor = UIColor.white
}
override func systemLayoutSizeFitting(_ targetSize: CGSize, withHorizontalFittingPriority horizontalFittingPriority: UILayoutPriority, verticalFittingPriority: UILayoutPriority) -> CGSize {
width.constant = bounds.size.width
return contentView.systemLayoutSizeFitting(CGSize(width: targetSize.width, height: 1))
}
func setupViews() {
// view setup happens here
if let lastSubview = contentView.subviews.last {
contentView.bottomAnchor.constraint(equalTo: lastSubview.bottomAnchor, constant: 0).isActive = true
}
}
同样，如果我将单元格用作常规单元格，而不是在 header 或 collectionView 的页脚中，此代码完全可以正常工作。
现在，我只是想在 header 中使用它。由于无法为 header 单元格提供类似 estimatedItemSize 的内容，因此我使用了以下方法，可在 this SO post:
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
let indexPath = IndexPath(row: 0, section: section)
let headerView = self.collectionView(collectionView, viewForSupplementaryElementOfKind: UICollectionView.elementKindSectionHeader, at: indexPath) as! TLContentCell
headerView.layoutIfNeeded()
return headerView.systemLayoutSizeFitting(CGSize(width: collectionView.frame.width, height: UIView.layoutFittingExpandedSize.height),
withHorizontalFittingPriority: .required, // Width is fixed
verticalFittingPriority: .fittingSizeLevel) // Height can be as large as needed
}
事实上，header 单元格调整大小正确。 然而，UIKit 打印看似无穷无尽的 UIViewAlertForUnsatisfiableConstraints 错误（由于 SO 字符限制而缩短）：
2020-01-16 15:29:00.427001+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x600000024820 MyApp.DefaultLabel:0x7fa6fc579090'3d'.width == 17.6667 (active)>",
"<NSLayoutConstraint:0x600000024780 MyApp.AnimatedButton:0x7fa6fc5786d0.width == 20 (active)>",
"<NSLayoutConstraint:0x6000000245f0 UIImageView:0x7fa6fc578020.width == 45 (active)>",
"<NSLayoutConstraint:0x600000024550 H:|-(0)-[UIImageView:0x7fa6fc578020](LTR) (active, names: '|':UIView:0x7fa6fc578980 )>",
"<NSLayoutConstraint:0x600000024730 MyApp.AnimatedButton:0x7fa6fc5786d0.right == UIView:0x7fa6fc578980.right (active)>",
"<NSLayoutConstraint:0x6000000247d0 MyApp.DefaultLabel:0x7fa6fc579090'3d'.right == MyApp.AnimatedButton:0x7fa6fc5786d0.left - 4 (active)>",
"<NSLayoutConstraint:0x600000024a50 H:[UIImageView:0x7fa6fc578020]-(8)-[MyApp.DefaultLabel:0x7fa6fc578460'@unitedholograms'](LTR) (active)>",
"<NSLayoutConstraint:0x600000024910 MyApp.DefaultLabel:0x7fa6fc578460'@unitedholograms'.right == MyApp.DefaultLabel:0x7fa6fc579090'3d'.left (active)>",
"<NSLayoutConstraint:0x600000024be0 H:|-(16)-[UIView:0x7fa6fc578980](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x600000024c30 UIView:0x7fa6fc578980.right == UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x6000000245f0 UIImageView:0x7fa6fc578020.width == 45 (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2020-01-16 15:29:00.427892+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x6000000252c0 UIStackView:0x7fa6fc57a470.width == 80 (active)>",
"<NSLayoutConstraint:0x600000024fa0 H:|-(0)-[UIImageView:0x7fa6fc57a610](LTR) (active, names: '|':UIView:0x7fa6fc57a300 )>",
"<NSLayoutConstraint:0x600000025040 UIImageView:0x7fa6fc57a610.right == UIStackView:0x7fa6fc57a470.left - 8 (active)>",
"<NSLayoutConstraint:0x600000025220 UIStackView:0x7fa6fc57a470.right == UIView:0x7fa6fc57a300.right (active)>",
"<NSLayoutConstraint:0x600000025360 H:|-(0)-[UIView:0x7fa6fc57a300](LTR) (active, names: '|':UIView:0x7fa6fc57a010 )>",
"<NSLayoutConstraint:0x6000000253b0 UIView:0x7fa6fc57a300.right == UIView:0x7fa6fc57a010.right (active)>",
"<NSLayoutConstraint:0x600000025590 H:|-(16)-[UIView:0x7fa6fc57a010](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x6000000255e0 UIView:0x7fa6fc57a010.right == UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x6000000252c0 UIStackView:0x7fa6fc57a470.width == 80 (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2020-01-16 15:29:00.428596+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x600000024820 MyApp.DefaultLabel:0x7fa6fc579090'3d'.width == 17.6667 (active)>",
"<NSLayoutConstraint:0x600000024780 MyApp.AnimatedButton:0x7fa6fc5786d0.width == 20 (active)>",
"<NSLayoutConstraint:0x600000024550 H:|-(0)-[UIImageView:0x7fa6fc578020](LTR) (active, names: '|':UIView:0x7fa6fc578980 )>",
"<NSLayoutConstraint:0x600000024730 MyApp.AnimatedButton:0x7fa6fc5786d0.right == UIView:0x7fa6fc578980.right (active)>",
"<NSLayoutConstraint:0x6000000247d0 MyApp.DefaultLabel:0x7fa6fc579090'3d'.right == MyApp.AnimatedButton:0x7fa6fc5786d0.left - 4 (active)>",
"<NSLayoutConstraint:0x600000024a50 H:[UIImageView:0x7fa6fc578020]-(8)-[MyApp.DefaultLabel:0x7fa6fc578460'@unitedholograms'](LTR) (active)>",
"<NSLayoutConstraint:0x600000024910 MyApp.DefaultLabel:0x7fa6fc578460'@unitedholograms'.right == MyApp.DefaultLabel:0x7fa6fc579090'3d'.left (active)>",
"<NSLayoutConstraint:0x600000024be0 H:|-(16)-[UIView:0x7fa6fc578980](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x600000024c30 UIView:0x7fa6fc578980.right == UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x600000024780 MyApp.AnimatedButton:0x7fa6fc5786d0.width == 20 (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2020-01-16 15:29:00.429543+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x600000024820 MyApp.DefaultLabel:0x7fa6fc579090'3d'.width == 17.6667 (active)>",
"<NSLayoutConstraint:0x600000024550 H:|-(0)-[UIImageView:0x7fa6fc578020](LTR) (active, names: '|':UIView:0x7fa6fc578980 )>",
"<NSLayoutConstraint:0x600000024730 MyApp.AnimatedButton:0x7fa6fc5786d0.right == UIView:0x7fa6fc578980.right (active)>",
"<NSLayoutConstraint:0x6000000247d0 MyApp.DefaultLabel:0x7fa6fc579090'3d'.right == MyApp.AnimatedButton:0x7fa6fc5786d0.left - 4 (active)>",
"<NSLayoutConstraint:0x600000024a50 H:[UIImageView:0x7fa6fc578020]-(8)-[MyApp.DefaultLabel:0x7fa6fc578460'@unitedholograms'](LTR) (active)>",
"<NSLayoutConstraint:0x600000024910 MyApp.DefaultLabel:0x7fa6fc578460'@unitedholograms'.right == MyApp.DefaultLabel:0x7fa6fc579090'3d'.left (active)>",
"<NSLayoutConstraint:0x600000024be0 H:|-(16)-[UIView:0x7fa6fc578980](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x600000024c30 UIView:0x7fa6fc578980.right == UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x600000024820 MyApp.DefaultLabel:0x7fa6fc579090'3d'.width == 17.6667 (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2020-01-16 15:29:00.430324+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x6000000250e0 V:|-(0)-[UIStackView:0x7fa6fc57a470] (active, names: '|':UIView:0x7fa6fc57a300 )>",
"<NSLayoutConstraint:0x600000025090 UIStackView:0x7fa6fc57a470.bottom == UIView:0x7fa6fc57a300.bottom (active)>",
"<NSLayoutConstraint:0x600000025400 UIView:0x7fa6fc57a300.height == 0.5625*UIView:0x7fa6fc57a300.width (active)>",
"<NSLayoutConstraint:0x600000025360 H:|-(0)-[UIView:0x7fa6fc57a300](LTR) (active, names: '|':UIView:0x7fa6fc57a010 )>",
"<NSLayoutConstraint:0x6000000253b0 UIView:0x7fa6fc57a300.right == UIView:0x7fa6fc57a010.right (active)>",
"<NSLayoutConstraint:0x600000025590 H:|-(16)-[UIView:0x7fa6fc57a010](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x6000000255e0 UIView:0x7fa6fc57a010.right == UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>",
"<NSLayoutConstraint:0x600000026210 'UISV-canvas-connection' UIStackView:0x7fa6fc57a470.top == UIImageView:0x7fa6fc57a7e0.top (active)>",
"<NSLayoutConstraint:0x600000026260 'UISV-canvas-connection' V:[UIImageView:0x7fa6fc57ab80]-(0)-| (active, names: '|':UIStackView:0x7fa6fc57a470 )>",
"<NSLayoutConstraint:0x600000026300 'UISV-fill-equally' UIImageView:0x7fa6fc57a9b0.height == UIImageView:0x7fa6fc57a7e0.height (active)>",
"<NSLayoutConstraint:0x6000000263a0 'UISV-fill-equally' UIImageView:0x7fa6fc57ab80.height == UIImageView:0x7fa6fc57a7e0.height (active)>",
"<NSLayoutConstraint:0x6000000262b0 'UISV-spacing' V:[UIImageView:0x7fa6fc57a7e0]-(8)-[UIImageView:0x7fa6fc57a9b0] (active)>",
"<NSLayoutConstraint:0x600000026350 'UISV-spacing' V:[UIImageView:0x7fa6fc57a9b0]-(8)-[UIImageView:0x7fa6fc57ab80] (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x600000026350 'UISV-spacing' V:[UIImageView:0x7fa6fc57a9b0]-(8)-[UIImageView:0x7fa6fc57ab80] (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2020-01-16 15:29:00.431297+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x60000003df90 UIImageView:0x7fa6fc576970.width == 13 (active)>",
"<NSLayoutConstraint:0x60000003e030 H:|-(4)-[UIImageView:0x7fa6fc576970](LTR) (active, names: '|':UIView:0x7fa6fc56e2d0 )>",
"<NSLayoutConstraint:0x60000003e940 H:[UIImageView:0x7fa6fc576970]-(4)-[MyApp.DefaultLabel:0x7fa6fc576700'by linus_hologram '](LTR) (active)>",
"<NSLayoutConstraint:0x60000003e440 MyApp.DefaultLabel:0x7fa6fc576700'by linus_hologram '.right == UIView:0x7fa6fc56e2d0.right - 4 (active)>",
"<NSLayoutConstraint:0x6000000e2bc0 H:|-(16)-[UIView:0x7fa6fc56e2d0](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x600000023930 UIView:0x7fa6fc56e2d0.right <= UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x600000025ae0 MyApp.DefaultLabel:0x7fa6fc575060'0'.right == UIView:0x7fa6fc57c3e0.right (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2020-01-16 15:29:00.434486+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x60000003e030 H:|-(4)-[UIImageView:0x7fa6fc576970](LTR) (active, names: '|':UIView:0x7fa6fc56e2d0 )>",
"<NSLayoutConstraint:0x60000003e940 H:[UIImageView:0x7fa6fc576970]-(4)-[MyApp.DefaultLabel:0x7fa6fc576700'by linus_hologram '](LTR) (active)>",
"<NSLayoutConstraint:0x60000003e440 MyApp.DefaultLabel:0x7fa6fc576700'by linus_hologram '.right == UIView:0x7fa6fc56e2d0.right - 4 (active)>",
"<NSLayoutConstraint:0x6000000e2bc0 H:|-(16)-[UIView:0x7fa6fc56e2d0](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x600000023930 UIView:0x7fa6fc56e2d0.right <= UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x60000003e940 H:[UIImageView:0x7fa6fc576970]-(4)-[MyApp.DefaultLabel:0x7fa6fc576700'by linus_hologram '](LTR) (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2020-01-16 15:29:00.435062+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x600000024550 H:|-(0)-[UIImageView:0x7fa6fc578020](LTR) (active, names: '|':UIView:0x7fa6fc578980 )>",
"<NSLayoutConstraint:0x600000024730 MyApp.AnimatedButton:0x7fa6fc5786d0.right == UIView:0x7fa6fc578980.right (active)>",
"<NSLayoutConstraint:0x6000000247d0 MyApp.DefaultLabel:0x7fa6fc579090'3d'.right == MyApp.AnimatedButton:0x7fa6fc5786d0.left - 4 (active)>",
"<NSLayoutConstraint:0x600000024a50 H:[UIImageView:0x7fa6fc578020]-(8)-[MyApp.DefaultLabel:0x7fa6fc578460'@unitedholograms'](LTR) (active)>",
"<NSLayoutConstraint:0x600000024910 MyApp.DefaultLabel:0x7fa6fc578460'@unitedholograms'.right == MyApp.DefaultLabel:0x7fa6fc579090'3d'.left (active)>",
"<NSLayoutConstraint:0x600000024be0 H:|-(16)-[UIView:0x7fa6fc578980](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x600000024c30 UIView:0x7fa6fc578980.right == UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x600000024a50 H:[UIImageView:0x7fa6fc578020]-(8)-[MyApp.DefaultLabel:0x7fa6fc578460'@unitedholograms'](LTR) (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2020-01-16 15:29:00.435727+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x600000024550 H:|-(0)-[UIImageView:0x7fa6fc578020](LTR) (active, names: '|':UIView:0x7fa6fc578980 )>",
"<NSLayoutConstraint:0x600000024730 MyApp.AnimatedButton:0x7fa6fc5786d0.right == UIView:0x7fa6fc578980.right (active)>",
"<NSLayoutConstraint:0x6000000247d0 MyApp.DefaultLabel:0x7fa6fc579090'3d'.right == MyApp.AnimatedButton:0x7fa6fc5786d0.left - 4 (active)>",
"<NSLayoutConstraint:0x600000024960 H:[UIImageView:0x7fa6fc578020]-(8)-[MyApp.DefaultLabel:0x7fa6fc5781f0'MyApp'](LTR) (active)>",
"<NSLayoutConstraint:0x6000000249b0 MyApp.DefaultLabel:0x7fa6fc5781f0'MyApp'.right == MyApp.DefaultLabel:0x7fa6fc579090'3d'.left (active)>",
"<NSLayoutConstraint:0x600000024be0 H:|-(16)-[UIView:0x7fa6fc578980](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x600000024c30 UIView:0x7fa6fc578980.right == UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x600000024960 H:[UIImageView:0x7fa6fc578020]-(8)-[MyApp.DefaultLabel:0x7fa6fc5781f0'MyApp'](LTR) (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2020-01-16 15:29:00.436212+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x600000024fa0 H:|-(0)-[UIImageView:0x7fa6fc57a610](LTR) (active, names: '|':UIView:0x7fa6fc57a300 )>",
"<NSLayoutConstraint:0x600000025040 UIImageView:0x7fa6fc57a610.right == UIStackView:0x7fa6fc57a470.left - 8 (active)>",
"<NSLayoutConstraint:0x600000025220 UIStackView:0x7fa6fc57a470.right == UIView:0x7fa6fc57a300.right (active)>",
"<NSLayoutConstraint:0x600000025360 H:|-(0)-[UIView:0x7fa6fc57a300](LTR) (active, names: '|':UIView:0x7fa6fc57a010 )>",
"<NSLayoutConstraint:0x6000000253b0 UIView:0x7fa6fc57a300.right == UIView:0x7fa6fc57a010.right (active)>",
"<NSLayoutConstraint:0x600000025590 H:|-(16)-[UIView:0x7fa6fc57a010](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x6000000255e0 UIView:0x7fa6fc57a010.right == UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x600000025220 UIStackView:0x7fa6fc57a470.right == UIView:0x7fa6fc57a300.right (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2020-01-16 15:29:00.436954+0100 MyApp[1542:65269] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x600000025680 H:|-(0)-[MyApp.PostInteractionButton:0x7fa6fc5720f0](LTR) (active, names: '|':UIView:0x7fa6fc579e80 )>",
"<NSLayoutConstraint:0x600000025720 MyApp.PostInteractionButton:0x7fa6fc5720f0.right == MyApp.DefaultLabel:0x7fa6fc573090'1'.left - 8 (active)>",
"<NSLayoutConstraint:0x600000025810 MyApp.DefaultLabel:0x7fa6fc573090'1'.right == UIView:0x7fa6fc579e80.right (active)>",
"<NSLayoutConstraint:0x600000025ef0 H:|-(16)-[UIStackView:0x7fa6fc579cf0](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x600000025540 UIStackView:0x7fa6fc579cf0.right == UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>",
"<NSLayoutConstraint:0x6000000265d0 'UISV-canvas-connection' UIStackView:0x7fa6fc579cf0.leading == UIView:0x7fa6fc579e80.leading (active)>",
"<NSLayoutConstraint:0x600000026620 'UISV-canvas-connection' H:[MyApp.PostInteractionButton:0x7fa6fc5752d0]-(0)-| (active, names: '|':UIStackView:0x7fa6fc579cf0 )>",
"<NSLayoutConstraint:0x6000000266c0 'UISV-distributing-edge' H:[UIView:0x7fa6fc579e80]-(0)-[_UIOLAGapGuide:0x600001f8cd00'UISV-distributing'] (active)>",
"<NSLayoutConstraint:0x600000026710 'UISV-distributing-edge' _UIOLAGapGuide:0x600001f8cd00'UISV-distributing'.trailing == UIView:0x7fa6fc57c3e0.leading (active)>",
"<NSLayoutConstraint:0x600000026800 'UISV-distributing-edge' H:[UIView:0x7fa6fc57c3e0]-(0)-[_UIOLAGapGuide:0x600001f8d300'UISV-distributing'] (active)>",
"<NSLayoutConstraint:0x600000026850 'UISV-distributing-edge' _UIOLAGapGuide:0x600001f8d300'UISV-distributing'.trailing == UIView:0x7fa6fc57c6d0.leading (active)>",
"<NSLayoutConstraint:0x6000000267b0 'UISV-distributing-edge' H:[UIView:0x7fa6fc57c6d0]-(0)-[_UIOLAGapGuide:0x600001f8d400'UISV-distributing'] (active)>",
"<NSLayoutConstraint:0x600000026940 'UISV-distributing-edge' _UIOLAGapGuide:0x600001f8d400'UISV-distributing'.trailing == MyApp.PostInteractionButton:0x7fa6fc5752d0.leading (active)>",
"<NSLayoutConstraint:0x6000000268a0 'UISV-fill-equally' _UIOLAGapGuide:0x600001f8d300'UISV-distributing'.width == _UIOLAGapGuide:0x600001f8cd00'UISV-distributing'.width (active)>",
"<NSLayoutConstraint:0x600000026990 'UISV-fill-equally' _UIOLAGapGuide:0x600001f8d400'UISV-distributing'.width == _UIOLAGapGuide:0x600001f8cd00'UISV-distributing'.width (active)>"
)
结尾
我真的不知道为什么会有这种行为。特别是如果我不将该单元格用作 header 单元格，一切都运行良好。
我们可以将这些错误插入 WTF Auto Layout? 并更好地了解正在发生的事情。
让我们从first one开始。最后 3 行在这里很有趣：
- View1 的前缘应等于 View2 的前缘加 16。
- View1 的后缘应等于 View2 的后缘减去 16。
- View2 的宽度应等于 0。
但是，看起来打破约束的是设置为 45 的图像视图的宽度。UIImageView:0x7fa6fc578020.width == 45
还有另一个约束将 imageView 和 View1 配对在一起：ImageView's leading edge should equal View1's leading edge.
有了这些细节，我们就可以开始构想它的布局了。
View2LeadingEdge - 16pts - View1LeadingEdge - ImageViewLeading - 45pts - ImageViewTrailing - View1TrailingEdge - 16pts - View2Trailing
对我来说，View2 的宽度为零似乎有些不对劲。请注意错误中的每组破坏约束，您会看到如下一行：
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>"
我想我需要更多的上下文来完成调试，但这应该能让您顺利开始。我不确定 View2 到底是什么，但我会尝试弄清楚为什么它的宽度设置为零。
您似乎并没有忘记禁用 translatesAutoResizingMask 或单元格自动添加此约束以强制布局，因此如果您无法弄清楚，您也可以尝试将优先级设置为 View1's trailing edge should equal View2's trailing edge minus 16. 到 .defaultHigh 以查看是否可以帮助自动布局引擎确定最佳布局。
也不要忘记检查此设置：
(
"<NSLayoutConstraint:0x600000025680 H:|-(0)-[MyApp.PostInteractionButton:0x7fa6fc5720f0](LTR) (active, names: '|':UIView:0x7fa6fc579e80 )>",
"<NSLayoutConstraint:0x600000025720 MyApp.PostInteractionButton:0x7fa6fc5720f0.right == MyApp.DefaultLabel:0x7fa6fc573090'1'.left - 8 (active)>",
"<NSLayoutConstraint:0x600000025810 MyApp.DefaultLabel:0x7fa6fc573090'1'.right == UIView:0x7fa6fc579e80.right (active)>",
"<NSLayoutConstraint:0x600000025ef0 H:|-(16)-[UIStackView:0x7fa6fc579cf0](LTR) (active, names: '|':UIView:0x7fa6fc56b450 )>",
"<NSLayoutConstraint:0x600000025540 UIStackView:0x7fa6fc579cf0.right == UIView:0x7fa6fc56b450.right - 16 (active)>",
"<NSLayoutConstraint:0x600000026fd0 UIView:0x7fa6fc56b450.width == 0 (active)>",
"<NSLayoutConstraint:0x6000000265d0 'UISV-canvas-connection' UIStackView:0x7fa6fc579cf0.leading == UIView:0x7fa6fc579e80.leading (active)>",
"<NSLayoutConstraint:0x600000026620 'UISV-canvas-connection' H:[MyApp.PostInteractionButton:0x7fa6fc5752d0]-(0)-| (active, names: '|':UIStackView:0x7fa6fc579cf0 )>",
"<NSLayoutConstraint:0x6000000266c0 'UISV-distributing-edge' H:[UIView:0x7fa6fc579e80]-(0)-[_UIOLAGapGuide:0x600001f8cd00'UISV-distributing'] (active)>",
"<NSLayoutConstraint:0x600000026710 'UISV-distributing-edge' _UIOLAGapGuide:0x600001f8cd00'UISV-distributing'.trailing == UIView:0x7fa6fc57c3e0.leading (active)>",
"<NSLayoutConstraint:0x600000026800 'UISV-distributing-edge' H:[UIView:0x7fa6fc57c3e0]-(0)-[_UIOLAGapGuide:0x600001f8d300'UISV-distributing'] (active)>",
"<NSLayoutConstraint:0x600000026850 'UISV-distributing-edge' _UIOLAGapGuide:0x600001f8d300'UISV-distributing'.trailing == UIView:0x7fa6fc57c6d0.leading (active)>",
"<NSLayoutConstraint:0x6000000267b0 'UISV-distributing-edge' H:[UIView:0x7fa6fc57c6d0]-(0)-[_UIOLAGapGuide:0x600001f8d400'UISV-distributing'] (active)>",
"<NSLayoutConstraint:0x600000026940 'UISV-distributing-edge' _UIOLAGapGuide:0x600001f8d400'UISV-distributing'.trailing == MyApp.PostInteractionButton:0x7fa6fc5752d0.leading (active)>",
"<NSLayoutConstraint:0x6000000268a0 'UISV-fill-equally' _UIOLAGapGuide:0x600001f8d300'UISV-distributing'.width == _UIOLAGapGuide:0x600001f8cd00'UISV-distributing'.width (active)>",
"<NSLayoutConstraint:0x600000026990 'UISV-fill-equally' _UIOLAGapGuide:0x600001f8d400'UISV-distributing'.width == _UIOLAGapGuide:0x600001f8cd00'UISV-distributing'.width (active)>"
)