有没有办法在不重置添加的最后一个视图的位置的情况下向 Xcode 添加子视图？

Question

这是我的代码：

let newView = ImageView()
    newView.translatesAutoresizingMaskIntoConstraints = false
    newView.backgroundColor = .random()
    view.addSubview(newView)

    newView.widthAnchor.constraint(equalToConstant: 100).isActive = true
    newView.heightAnchor.constraint(equalToConstant: 100).isActive = true
    newView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
    newView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true

    let panGR = UIPanGestureRecognizer(target: self, action: #selector(handlePan))
    panGR.delegate = self
    newView.addGestureRecognizer(panGR)

    let pinchGR = UIPinchGestureRecognizer(target: self, action: #selector(handlePinch(pinch:)))
    pinchGR.delegate = self
    newView.addGestureRecognizer(pinchGR)

    let rotateGR = UIRotationGestureRecognizer(target: self, action: #selector(handleRotate(rotate:)))
    rotateGR.delegate = self
    newView.addGestureRecognizer(rotateGR)

每次按下按钮时，它都会运行此代码。但是，所有子视图都在不断重置它们的位置。

这是“handlePan”的代码：

@objc func handlePan(_ gestureRecognizer : UIPanGestureRecognizer){
    if gestureRecognizer.state == .began || gestureRecognizer.state == .changed {
        let translation = gestureRecognizer.translation(in: self.view)
        gestureRecognizer.view!.center = CGPoint(x: gestureRecognizer.view!.center.x + translation.x, y: gestureRecognizer.view!.center.y + translation.y)

        gestureRecognizer.setTranslation(CGPoint.zero, in: self.view)


    }
}

Answer 1

因为您在自定义视图创建时设置了约束。

将自定义视图添加到超级视图后，您可以通过拖动更改其位置 - 但您只需更改 center 属性即可。好的。

当您向您的超级视图添加新的自定义视图时 - 将执行布局子视图。并且您所有的子视图位置都将根据初始约束进行重置。

你需要：

• 不要在子视图中使用约束

• 在您的handlePan(_ gestureRecognizer : UIPanGestureRecognizer) 函数更改中 centerXAnchor,centerYAnchor 约束值，不是中心属性。因为在任何布局子视图之后，它们的位置都会被设置为原来的。

  let newView = UIImageView.init(frame: .init(x: 0, y: 0, width: 100, height: 100))
  newView.translatesAutoresizingMaskIntoConstraints = false
  newView.isUserInteractionEnabled = true
  newView.backgroundColor = UIColor.random
  view.addSubview(newView)
  
  // newView.widthAnchor.constraint(equalToConstant: 100).isActive = true
  // newView.heightAnchor.constraint(equalToConstant: 100).isActive = true
  // newView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
  // newView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
  
  let panGR = UIPanGestureRecognizer(target: self, action: #selector(handlePan))
  panGR.delegate = self
  newView.addGestureRecognizer(panGR)
  

这段代码运行良好。

有约束的版本：

@IBAction func addView() {
    let newView = CustomView.init()
    newView.translatesAutoresizingMaskIntoConstraints = false
    newView.isUserInteractionEnabled = true
    newView.backgroundColor = UIColor.random
    view.addSubview(newView)

    newView.widthAnchor.constraint(equalToConstant: 100).isActive = true
    newView.heightAnchor.constraint(equalToConstant: 100).isActive = true
    newView.centerXConstraint = newView.centerXAnchor.constraint(equalTo: view.centerXAnchor)
    newView.centerYConstraint = newView.centerYAnchor.constraint(equalTo: view.centerYAnchor)
    newView.centerXConstraint.isActive = true
    newView.centerYConstraint.isActive = true

    let panGR = UIPanGestureRecognizer(target: self, action: #selector(handlePan))
    panGR.delegate = self
    newView.addGestureRecognizer(panGR)
}

@objc func handlePan(_ gestureRecognizer : UIPanGestureRecognizer){
    if gestureRecognizer.state == .began || gestureRecognizer.state == .changed,
        let view = gestureRecognizer.view as? CustomView,
        let centerXConstraint = view.centerXConstraint,
        let centerYConstraint = view.centerYConstraint {
        let translation = gestureRecognizer.translation(in: self.view)
        let x = centerXConstraint.constant + translation.x
        let y = centerYConstraint.constant + translation.y
        centerXConstraint.constant = x
        centerYConstraint.constant = y
        gestureRecognizer.setTranslation(CGPoint.zero, in: self.view)
    }
}

在您的自定义类中添加约束变量

class CustomView: UIView {
    var centerXConstraint: NSLayoutConstraint!
    var centerYConstraint: NSLayoutConstraint!

}