使用 UITapGestureRecognizer 点击后如何保护 UIView

Question

我尝试为屏幕上的每次点击添加 UIView，但是一旦我点击了 UIView，但我无法在屏幕上保护他，当我取消点击时他就消失了。我应该怎么做才能在屏幕上安全地显示 UIView，然后点击一次以添加第二个 UIView 并保存我的每个 UIView？

import UIKit

class ViewController: UIViewController {
    
    // MARK: - Property
    
    let circle: UIView = {
        let circle = UIView()
        circle.frame.size.height = 100
        circle.frame.size.width = 100
        circle.layer.borderWidth = 10
        circle.layer.borderColor = UIColor.white.cgColor
        circle.layer.cornerRadius = 50
        return circle
    }()
    
    // MARK: - LifeCycle

    override func viewDidLoad() {
        super.viewDidLoad()
        
        addRecognizer()
        view.backgroundColor = .red
    }
    
    // MARK: - Methods
    
    @IBAction func tappedRecognizer(_ recognizer: UITapGestureRecognizer) {
        
        let tapLocation = recognizer.location(in: view)
        let circleHeight = circle.frame.size.height
        let circleWidth = circle.frame.size.width
        print(tapLocation)
        circle.frame.origin = .init(x: tapLocation.x - circleWidth/2, y: tapLocation.y - circleHeight/2)
        view.addSubview(circle)
    }
    
    func addRecognizer() {
        
        let recognizer = UITapGestureRecognizer(target: self, action: #selector(tappedRecognizer(_:)))
        self.view.addGestureRecognizer(recognizer)
    }
    
}

Answer 1

在您的 class 中添加数组和创建新圈子的方法：

class ViewController: UIViewController {

    // MARK: - Property
    var circles = [UIView]()

    func newCircle(atLocation tapLocation: CGPoint) -> UIView {
        let circle = UIView()
        circle.frame.size.height = 100
        circle.frame.size.width = 100
        circle.layer.borderWidth = 10
        circle.layer.borderColor = UIColor.white.cgColor
        circle.layer.cornerRadius = 50
        circle.frame.origin = .init(x: tapLocation.x - circle.frame.size.width/2, 
                                    y: tapLocation.y - circle.frame.size.height/2)
        circles.append(circle)
        return circle
    }

    @IBAction func tappedRecognizer(_ recognizer: UITapGestureRecognizer) {
        let tapLocation = recognizer.location(in: view)
        print(tapLocation)
        let circle = newCircle(atLocation: tapLocation)
        view.addSubview(circle)
        }
    }

另一种方法是使用计算属性（这可能是您尝试实现的）。为此，只需从属性定义中删除 = :

    let circle: UIView { /: no =
        get {
            let circle = UIView()
            circle.frame.size.height = 100
            circle.frame.size.width = 100
            circle.layer.borderWidth = 10
            circle.layer.borderColor = UIColor.white.cgColor
            circle.layer.cornerRadius = 50
            return circle
        }
    } // no ()

使用 UITapGestureRecognizer 点击后如何保护 UIView

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