每次调用Func时，UIView都会被覆盖

问题描述

我的快速代码目标是每次按下按钮时都放置一个uiview。在我的gif中，您可以看到每次调用蓝色按钮都被覆盖。按下代码后，gif中将包含2个uiviews。您可以看到第一个视图消失的透明uiview。基本上，此代码的所有错误之处在于，当调用addBlackView时，它应该基本上像一个无限数组一样添加到屏幕上的视图中。

import UIKit
class ViewController: UIViewController {

var image1Width2: NSLayoutConstraint!
var iHieght: NSLayoutConstraint!

override func viewDidLoad() {
    super.viewDidLoad()
    view.backgroundColor = .white

    view.addSubview(slider)
    slider.translatesAutoresizingMaskIntoConstraints = false
    slider.value = 0.5
    slider.isUserInteractionEnabled = true
    NSLayoutConstraint.activate([
        slider.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor),slider.leadingAnchor.constraint(equalTo: view.leadingAnchor),slider.heightAnchor.constraint(equalToConstant: 100),slider.widthAnchor.constraint(equalTo: view.widthAnchor,multiplier: 1),])

    view.addSubview(button)
    button.translatesAutoresizingMaskIntoConstraints = false
    NSLayoutConstraint.activate([
        button.trailingAnchor.constraint(equalTo: view.trailingAnchor,constant: -16),button.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor,constant: 16),button.widthAnchor.constraint(equalToConstant: 100),button.heightAnchor.constraint(equalToConstant: 80),])
    button.addTarget(self,action: #selector(addBlackView),for: .touchUpInside)
    slider.addTarget(self,action: #selector(increase),for: .allEvents)

}

let slider:UiSlider = {
    let slider = UiSlider(frame: .zero)
    return slider
}()

private lazy var button: UIButton = {
    let button = UIButton()
    button.backgroundColor = .blue
    button.setTitleColor(.white,for: .normal)
    button.setTitle("add",for: .normal)
    return button
}()

let blackView: UIView = {
    let view = UIView()
    view.backgroundColor = .black
    return view
}()

@objc
private func addBlackView() {
    self.view.addSubview(blackView)
    blackView.translatesAutoresizingMaskIntoConstraints = false
    blackView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
    blackView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
    image1Width2 = blackView.widthAnchor.constraint(equalTo: view.widthAnchor,multiplier: 0.1)
    image1Width2.isActive = true
    iHieght = blackView.heightAnchor.constraint(equalTo: view.heightAnchor,multiplier: 0.1)
    iHieght.isActive = true
    view.layoutIfNeeded()

    let recognizer = UIPanGestureRecognizer(target: self,action: #selector(moveView(_:)))
    blackView.addGestureRecognizer(recognizer)
}

@objc private func moveView(_ recognizer: UIPanGestureRecognizer) {
    switch recognizer.state {
    case .began:
        print("gesture began")
    case .changed:
        let translation = recognizer.translation(in: self.view)

        recognizer.view!.center = .init(x: recognizer.view!.center.x + translation.x,y: recognizer.view!.center.y + translation.y)
        recognizer.setTranslation(.zero,in: self.view)
    default:
        break
    }
}

@objc func increase() {
    image1Width2.constant = CGFloat(slider.value) * view.frame.size.width * 0.10
    iHieght.constant = CGFloat(slider.value) * view.frame.size.width * 0.10
}}

解决方法

问题是您每次执行blackView时都会重复使用和重置addBlackView，因此所做的更改将丢失（因此为什么视图在您返回后回到中心按下按钮）。

您需要在addBlackView中创建一个完整的新视图，该视图将是您正在操作的“ currentView”，然后向其中添加添加手势识别器。然后，再次执行addBlackView后，“ currentView”将被“验证”（存储在数组中或进行任何处理），然后创建另一个要操作的文件。

类似这样的东西：

private func addBlackView() {
    let newBlackView = UIView(frame: CGRect(0,10,10)) // whatever frame you want
    self.view.addSubview(newBlackView)
    self.currentView = newBlackView
}

nslayoutconstraint swift swift swift