iOS 正在添加多个 CALayer，但只应用了一个

Question

我想在我的文本字段中添加 left/right 边框。它是一个 IBOutlet。此外，如果我还添加了函数以在 didEdit 委托回调中设置文本字段的样式，它将正确更新。

这是我的代码。在 ViewDidLoad 内部。

let leftLayer = CALayer()
    leftLayer.frame = CGRect(x: 0, y: 0, width: 1, height: (password.frame.size.height - 1))
    leftLayer.backgroundColor = UIColor.gray.cgColor

    let rightLayer = CALayer()
    rightLayer.frame = CGRect(x: password.frame.size.width - 1, y: 0, width: 1, height: (password.frame.size.height - 1))
    rightLayer.backgroundColor = UIColor.gray.cgColor

    password.layer.setNeedsDisplay()
    password.layer.addSublayer(leftLayer)
    password.layer.display()

    password.layer.setNeedsDisplay()
    password.layer.addSublayer(rightLayer)
    password.layer.display()

除了

我已经删除了所有代码

  let rightLayer = CALayer()
    rightLayer.frame = CGRect(x: password.frame.size.width - 1, y: 0, width: 1, height: (password.frame.size.height - 1))
    rightLayer.backgroundColor = UIColor.gray.cgColor
    password.layer.setNeedsDisplay()
    password.layer.addSublayer(rightLayer)
    password.layer.display()

但是iOS根本不会添加这一层。我尝试了下面的代码片段

var once = true
override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()
    if once {
        styleTextViews()
        once = false
    }
}

唯一可行的是如果我从

调用它

 func textFieldDidBeginEditing(_ textField: UITextField) {
    styleTextViews()
}

然后添加就好了..

Answer 1

您的问题在 ViewDidLoad 您需要在 viewDidLayoutSubviews 中设置此代码，因为它包含正确的框架

var once  = true // as the function runs multiple times 

override func viewDidLayoutSubviews() {
  super.viewDidLayoutSubviews()
  if once {
   //  here 
    once = false
  }
}

iOS 正在添加多个 CALayer，但只应用了一个

iOS multiple CALayers being added but only one gets applied

calayer

ios

swift