每次调用 Func 时都会重写 UIView

Question

我的 swift 代码目标是每次按下按钮时放置一个 uiview。 在我的 gif 中，您可以看到每次调用蓝色按钮时都会被覆盖。 当按下代码时，gif 中应该有 2 个 uiviews。 您可以看到第一个视图消失的透明uiview。 基本上，这段代码的所有错误在于当 addBlackView 被调用时，它应该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
}}

Answer 1

问题是，你打算重用和重置blackView每次执行时间addBlackView ，所以您所做的更改将丢失（所以为什么认为可以追溯到在中心，你按下按钮后）。

您需要在addBlackView创建一个完整的新视图，这将是您正在操作的“currentView”，然后向其中添加手势识别器。 然后一旦你再次执行addBlackView ，'currentView' 将被'验证'（存储在一个数组或任何你需要用它做的事情中），然后你创建另一个来操作。

像这样的东西：

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