UIStackView 边界在创建后为零

Question

我有一个 UIStackView

的子class

final class MyStack : UIStackView {
  required init(coder: NSCoder) {
    super.init(coder: coder)
    setup()
  }
  
  override init(frame: CGRect) {
    super.init(frame: frame)
    setup()
  }
  
  private func setup() {
    backgroundColor = .clear
    axis = .horizontal
    contentMode = .scaleAspectFit
    
    alignment = .fill
    distribution = .fillProportionally
    spacing = 0
    
    contentMode = .scaleToFill
    isUserInteractionEnabled = true
    
    autoresizingMask = [.flexibleLeftMargin, .flexibleRightMargin, .flexibleTopMargin, .flexibleBottomMargin, .flexibleWidth, .flexibleHeight]
    translatesAutoresizingMaskIntoConstraints = true
    
  }

func setupSymbols(_ amount:Int) {
  let large = UIImage.SymbolConfiguration(scale: .large)

  for index in 0..< number {
    let image = UIImage(systemName: "trash", withConfiguration: large)
    let highlightedImage = UIImage(systemName: "trash.fill", withConfiguration: large)

    let imageView = UIImageView(image: image, highlightedImage: highlightedImage)
    self.addArrangedSubview(oneStar)
  }
}

在 ViewController 我创建了这个 class

的一个实例

let myStack = MyStack()

myStack.setupSymbols(5)
self.view.addSubview(myStack)

print (myStack.frame)

最后一行让我的宽度和高度等于零！！！

为什么？

Answer 1

直到下一个布局阶段，视图的框架才会更新。将视图添加到视图层次结构后不会立即计算框架，这就是为什么您看到它为零的原因。

如果您覆盖视图控制器的 viewDidLayoutSubviews 方法并检查那里的框架，它可能是 non-zero。

UIStackView 边界在创建后为零

UIStackView bounds is zero after creation

uikit

ios

uistackview