如何以编程方式使用安全区域布局？

Question

因为我不使用故事板来创建我的视图，所以我想知道是否有 "Use Safe Area Guides" 选项以编程方式或类似的方式。

我试图将我的观点固定在

view.safeAreaLayoutGuide

但它们在 iPhone X 模拟器中一直处于领先地位。

Answer 1

这里是示例代码（参考自：Safe Area Layout Guide）：
如果您在代码中创建约束，请使用 UIView 的 safeAreaLayoutGuide 属性获取相关的布局锚点。让我们在代码中重新创建上面的 Interface Builder 示例，看看它的外观：

假设我们在视图控制器中将绿色视图作为属性：

private let greenView = UIView()

我们可能有一个函数来设置从 viewDidLoad 调用的视图和约束：

private func setupView() {
  greenView.translatesAutoresizingMaskIntoConstraints = false
  greenView.backgroundColor = .green
  view.addSubview(greenView)
}

一如既往地使用根视图的 layoutMarginsGuide 创建前导和尾随边距约束：

 let margins = view.layoutMarginsGuide
 NSLayoutConstraint.activate([
    greenView.leadingAnchor.constraint(equalTo: margins.leadingAnchor),
    greenView.trailingAnchor.constraint(equalTo: margins.trailingAnchor)
 ])

现在，除非您的目标是 iOS 11 及更高版本，否则您将需要使用 #available 包装安全区域布局指南约束，并回退到早期 iOS 的顶部和底部布局指南版本：

if #available(iOS 11, *) {
  let guide = view.safeAreaLayoutGuide
  NSLayoutConstraint.activate([
   greenView.topAnchor.constraintEqualToSystemSpacingBelow(guide.topAnchor, multiplier: 1.0),
   guide.bottomAnchor.constraintEqualToSystemSpacingBelow(greenView.bottomAnchor, multiplier: 1.0)
   ])
} else {
   let standardSpacing: CGFloat = 8.0
   NSLayoutConstraint.activate([
   greenView.topAnchor.constraint(equalTo: topLayoutGuide.bottomAnchor, constant: standardSpacing),
   bottomLayoutGuide.topAnchor.constraint(equalTo: greenView.bottomAnchor, constant: standardSpacing)
   ])
}

结果：

这是 Safe Area Layout Guide

的 Apple 开发者官方文档

需要安全区域来处理 iPhone-X 的用户界面设计。这是 How to design user interface for iPhone-X using Safe Area Layout

的基本准则

Answer 2

我正在使用它而不是向 layoutMarginsGuide 添加前导和尾随边距约束：

UILayoutGuide *safe = self.view.safeAreaLayoutGuide;
yourView.translatesAutoresizingMaskIntoConstraints = NO;
[NSLayoutConstraint activateConstraints:@[
                                           [safe.trailingAnchor constraintEqualToAnchor:yourView.trailingAnchor],
                                           [yourView.leadingAnchor constraintEqualToAnchor:safe.leadingAnchor],
                                           [yourView.topAnchor constraintEqualToAnchor:safe.topAnchor],
                                           [safe.bottomAnchor constraintEqualToAnchor:yourView.bottomAnchor]
                                          ]];

请同时从 Krunal 的回答中检查 ios 11 的低版本选项。

Answer 3

SafeAreaLayoutGuide 是 UIView 属性,

The top of the safeAreaLayoutGuide indicates the unobscured top edge of the view (e.g, not behind the status bar or navigation bar, if present). Similarly for the other edges.

使用 safeAreaLayoutGuide 避免我们的对象 clipping/overlapping 来自圆角、导航栏、标签栏、工具栏和其他祖先视图。

我们可以分别创建safeAreaLayoutGuide对象和设置对象约束。

纵向 + 横向的约束是 -

        self.edgesForExtendedLayout = []//Optional our as per your view ladder

        let newView = UIView()
        newView.backgroundColor = .red
        self.view.addSubview(newView)
        newView.translatesAutoresizingMaskIntoConstraints = false
        if #available(iOS 11.0, *) {
            let guide = self.view.safeAreaLayoutGuide
            newView.trailingAnchor.constraint(equalTo: guide.trailingAnchor).isActive = true
            newView.leadingAnchor.constraint(equalTo: guide.leadingAnchor).isActive = true
            newView.topAnchor.constraint(equalTo: guide.topAnchor).isActive = true
            newView.heightAnchor.constraint(equalToConstant: 100).isActive = true

        }
        else {
            NSLayoutConstraint(item: newView, attribute: .top, relatedBy: .equal, toItem: view, attribute: .top, multiplier: 1.0, constant: 0).isActive = true
            NSLayoutConstraint(item: newView, attribute: .leading, relatedBy: .equal, toItem: view, attribute: .leading, multiplier: 1.0, constant: 0).isActive = true
            NSLayoutConstraint(item: newView, attribute: .trailing, relatedBy: .equal, toItem: view, attribute: .trailing, multiplier: 1.0, constant: 0).isActive = true

            newView.heightAnchor.constraint(equalToConstant: 100).isActive = true
        }

UILayoutGuide

safeAreaLayoutGuide

Answer 4

对于那些像我一样使用 SnapKit 的人，解决方案是将您的约束锚定到 view.safeAreaLayoutGuide，如下所示：

yourView.snp.makeConstraints { (make) in
    if #available(iOS 11.0, *) {
        //Bottom guide
        make.bottom.equalTo(view.safeAreaLayoutGuide.snp.bottomMargin)
        //Top guide
        make.top.equalTo(view.safeAreaLayoutGuide.snp.topMargin)
        //Leading guide
        make.leading.equalTo(view.safeAreaLayoutGuide.snp.leadingMargin)
        //Trailing guide
        make.trailing.equalTo(view.safeAreaLayoutGuide.snp.trailingMargin)

     } else {
        make.edges.equalToSuperview()
     }
}

Answer 5

我实际上正在为它使用扩展名并控制它是否是 iOS 11。

extension UIView {

  var safeTopAnchor: NSLayoutYAxisAnchor {
    if #available(iOS 11.0, *) {
      return safeAreaLayoutGuide.topAnchor
    }
    return topAnchor
  }

  var safeLeftAnchor: NSLayoutXAxisAnchor {
    if #available(iOS 11.0, *){
      return safeAreaLayoutGuide.leftAnchor
    }
    return leftAnchor
  }

  var safeRightAnchor: NSLayoutXAxisAnchor {
    if #available(iOS 11.0, *){
      return safeAreaLayoutGuide.rightAnchor
    }
    return rightAnchor
  }

  var safeBottomAnchor: NSLayoutYAxisAnchor {
    if #available(iOS 11.0, *) {
      return safeAreaLayoutGuide.bottomAnchor
    }
    return bottomAnchor
  }
}

Answer 6

使用视觉格式的约束，您可以免费获得对安全区域的尊重。

class ViewController: UIViewController {

    var greenView = UIView()

    override func viewDidLoad() {
        super.viewDidLoad()
        greenView.backgroundColor = .green
        view.addSubview(greenView)
    }
    override func viewWillLayoutSubviews() {
        super.viewWillLayoutSubviews()

        greenView.translatesAutoresizingMaskIntoConstraints = false
        let views : [String:Any] = ["greenView":greenView]
        view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-[greenView]-|", options: [], metrics: nil, views: views))
        view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|-[greenView]-|", options: [], metrics: nil, views: views))
    }
}

Answer 7

使用UIWindow或UIView的safeAreaInsets.bottom.top.left.right

// #available(iOS 11.0, *)
// height - UIApplication.shared.keyWindow!.safeAreaInsets.bottom

// On iPhoneX
// UIApplication.shared.keyWindow!.safeAreaInsets.top =  44
// UIApplication.shared.keyWindow!.safeAreaInsets.bottom = 34

// Other devices
// UIApplication.shared.keyWindow!.safeAreaInsets.top =  0
// UIApplication.shared.keyWindow!.safeAreaInsets.bottom = 0

// example
let window = UIApplication.shared.keyWindow!
let viewWidth = window.frame.size.width
let viewHeight = window.frame.size.height - window.safeAreaInsets.bottom
let viewFrame = CGRect(x: 0, y: 0, width: viewWidth, height: viewHeight)
let aView = UIView(frame: viewFrame)
aView.backgroundColor = .red
view.addSubview(aView)
aView.autoresizingMask = [.flexibleWidth, .flexibleHeight]

Answer 8

您可以按照此处的说明使用 view.safeAreaInsets https://www.raywenderlich.com/174078/auto-layout-visual-format-language-tutorial-2

代码示例（取自raywenderlich.com）：

override func viewSafeAreaInsetsDidChange() {
  super.viewSafeAreaInsetsDidChange()

  if !allConstraints.isEmpty {
    NSLayoutConstraint.deactivate(allConstraints)
    allConstraints.removeAll()
  }

  let newInsets = view.safeAreaInsets
  let leftMargin = newInsets.left > 0 ? newInsets.left : Metrics.padding
  let rightMargin = newInsets.right > 0 ? newInsets.right : Metrics.padding
  let topMargin = newInsets.top > 0 ? newInsets.top : Metrics.padding
  let bottomMargin = newInsets.bottom > 0 ? newInsets.bottom : Metrics.padding

  let metrics = [
    "horizontalPadding": Metrics.padding,
    "iconImageViewWidth": Metrics.iconImageViewWidth,
    "topMargin": topMargin,
    "bottomMargin": bottomMargin,
    "leftMargin": leftMargin,
    "rightMargin": rightMargin]
}


let views: [String: Any] = [
  "iconImageView": iconImageView,
  "appNameLabel": appNameLabel,
  "skipButton": skipButton,
  "appImageView": appImageView,
  "welcomeLabel": welcomeLabel,
  "summaryLabel": summaryLabel,
  "pageControl": pageControl]

let iconVerticalConstraints = NSLayoutConstraint.constraints(
  withVisualFormat: "V:|-topMargin-[iconImageView(30)]",
  metrics: metrics,
  views: views)
allConstraints += iconVerticalConstraints

let topRowHorizontalFormat = """
  H:|-leftMargin-[iconImageView(iconImageViewWidth)]-[appNameLabel]-[skipButton]-rightMargin-|
  """
...

Answer 9

Objective-C

的安全区域扩展

@implementation UIView (SafeArea)

- (NSLayoutAnchor *)safeTopAnchor{

    if (@available(iOS 11.0, *)){
        return self.safeAreaLayoutGuide.topAnchor;
    } else {
        return self.topAnchor;
    }

}


- (NSLayoutAnchor *)safeBottomAnchor{

    if (@available(iOS 11.0, *)) {
        return self.safeAreaLayoutGuide.bottomAnchor;
    } else {
        return self.bottomAnchor;
    }

}

@end

Answer 10

Swift 4.2 和 5.0。假设你想在 viewBug 上添加 Leading、Trailing、Top 和 Bottom 约束。所以，你可以使用下面的代码。

let guide = self.view.safeAreaLayoutGuide
viewBg.trailingAnchor.constraint(equalTo: guide.trailingAnchor).isActive = true
viewBg.leadingAnchor.constraint(equalTo: guide.leadingAnchor).isActive = true
viewBg.topAnchor.constraint(equalTo: guide.topAnchor).isActive = true
viewBg.bottomAnchor.constraint(equalTo: guide.bottomAnchor).isActive = true

Answer 11

此扩展可帮助您将 UIVIew 约束到其父视图和父视图+safeArea：

extension UIView {

    ///Constraints a view to its superview
    func constraintToSuperView() {
        guard let superview = superview else { return }
        translatesAutoresizingMaskIntoConstraints = false

        topAnchor.constraint(equalTo: superview.topAnchor).isActive = true
        leftAnchor.constraint(equalTo: superview.leftAnchor).isActive = true
        bottomAnchor.constraint(equalTo: superview.bottomAnchor).isActive = true
        rightAnchor.constraint(equalTo: superview.rightAnchor).isActive = true
    }

    ///Constraints a view to its superview safe area
    func constraintToSafeArea() {
        guard let superview = superview else { return }
        translatesAutoresizingMaskIntoConstraints = false

        topAnchor.constraint(equalTo: superview.safeAreaLayoutGuide.topAnchor).isActive = true
        leftAnchor.constraint(equalTo: superview.safeAreaLayoutGuide.leftAnchor).isActive = true
        bottomAnchor.constraint(equalTo: superview.safeAreaLayoutGuide.bottomAnchor).isActive = true
        rightAnchor.constraint(equalTo: superview.safeAreaLayoutGuide.rightAnchor).isActive = true
    }

}

如何以编程方式使用安全区域布局？

How do I use Safe Area Layout programmatically?

ios

swift

iphone-x

safearealayoutguide