arrays - 在视图控制器上放置无限的 uiview 对象数组

Question

下面的 swift 代码的目标是当调用 pressBtn 函数时，将单个黑色视图添加到屏幕中心。这段代码中的uiview叫做box。每次将框添加到屏幕的中心时，它都应该连接到一个 uipangesture，它可以让它四处移动，你可以在下面的 gif 中看到我在寻找什么。黑框被替换为 gif 的 x。

标签： arraysswiftlinked-listuipangesturerecognizerinfinite

Answer 1

您可以使用函数创建每个视图：

private func getBlackView() -> UIView {
    let view = UIView()
    view.backgroundColor = .black
    let sideLength: CGFloat = 100
    view.frame = .init(x: self.view.bounds.midX - sideLength / 2,
                       y: self.view.bounds.midY - sideLength / 2,
                       width: sideLength,
                       height: sideLength)
    let recognizer = UIPanGestureRecognizer(target: self,
                                            action: #selector(moveView(_:)))
    view.addGestureRecognizer(recognizer)
    return view
}

---

然后，在此函数中创建UIPanGestureRecognizer并将其添加到每个新创建的视图中。这个#selector识别器的应该是：

@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
    }
}

每次你得到一个识别的gecture并且状态是.changed时，你应该通过当前移动你的视图translation并重置它。

---

例子：

public class MyViewController : UIViewController {
    public override func viewDidLoad() {
        super.viewDidLoad()
        button.frame = .init(x: self.view.bounds.midX,
                             y: 0,
                             width: 100,
                             height: 100)
        self.view.addSubview(button)
    }
    
    private lazy var button: UIButton = {
        let button = UIButton()
        button.backgroundColor = .blue
        button.setTitleColor(.white, for: .normal)
        button.setTitle("add", for: .normal)
        button.addTarget(self,
                         action: #selector(addBlackView),
                         for: .touchUpInside)
        return button
    }()
    
    private func getBlackView() -> UIView {
        let view = UIView()
        view.backgroundColor = .black
        let sideLength: CGFloat = 100
        view.frame = .init(x: self.view.bounds.midX - sideLength / 2,
                           y: self.view.bounds.midY - sideLength / 2,
                           width: sideLength,
                           height: sideLength)
        let recognizer = UIPanGestureRecognizer(target: self,
                                                action: #selector(moveView(_:)))
        view.addGestureRecognizer(recognizer)
        return view
    }
    
    @objc 
    private func addBlackView() {
        let view = getBlackView()
        self.view.addSubview(view)
    }
    
    @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
        }
    }
}