将子视图添加到具有遮罩视图的视图会从中移除遮罩

Question

正如标题所说，我将self.view 添加到其mask（链接）属性中的另一个视图，但是当我使用addSubview 向self.view 添加更多视图时，掩码被移除。这是为什么？谢谢

我最初遇到this 的问题，并意识到mask 视图正在被释放。

在我的示例中，我添加了动画UIImageViews，当我在addView 中点击屏幕时，它会在UIBezierPath 上进行动画处理。

代码如下：

protocol UICircleMaskDelegate {

    func circleMaskCompletion()

}

class UICircleMask: UIView {

    var delegate: UICircleMaskDelegate?
    var gestureDelegate: UIGestureRecognizerDelegate?

    init(gestureDelegate: UIGestureRecognizerDelegate? = nil) {
        super.init(frame: .zero)
        self.gestureDelegate = gestureDelegate
        self.clipsToBounds = true
        self.backgroundColor = .yellow
        self.isUserInteractionEnabled = false
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    var diameterConstraint: NSLayoutConstraint?
    var animating = false

    func updateSize(_ delta: CGFloat, animated: Bool = false) {

        if animating { return }
        if animated {
            animating = true
            diameterConstraint?.constant = UIScreen.main.bounds.height * 2.1

            let duration: TimeInterval = Double((UIScreen.main.bounds.height - self.frame.height / 2.1) / 600)// duration = way / speed
            let animation = CABasicAnimation(keyPath: "cornerRadius")
            animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseOut)
            animation.fromValue = self.layer.cornerRadius
            animation.toValue = UIScreen.main.bounds.height * 2.1 / 2
            animation.duration = duration
            self.layer.add(animation, forKey: nil)

            UIView.animate(withDuration: duration, delay: 0, options: [.curveEaseOut], animations: {
                self.superview?.layoutIfNeeded()
            }, completion: { (success) in
                if success {
                    self.animating = false
                    self.delegate?.circleMaskCompletion()
                }
            })
        } else {
            let newSize = diameterConstraint!.constant + (delta * 2.85)
            if newSize > 60 && newSize < UIScreen.main.bounds.height * 2.1 {
                diameterConstraint?.constant = newSize
            }
        }

    }

    var panStarted = false

    func handlePan(_ pan: UIPanGestureRecognizer) {
        guard let superv = superview else { return }
        let delta = pan.translation(in: superv).y
        if pan.state == .began {
            if delta > 0 {
                panStarted = true
                updateSize(-delta)
            }
        } else if pan.state == .changed {
            if panStarted {
                updateSize(-delta)
            }
        } else if pan.state == .ended || pan.state == .cancelled {
            if panStarted {
                updateSize(superv.frame.height * 2.1, animated: true)
                panStarted = false
            }
        }
        pan.setTranslation(.zero, in: superv)
    }

    override func didMoveToSuperview() {
        super.didMoveToSuperview()
        if let superv = superview {
            //
            self.makeSquare()
            self.centerHorizontallyTo(superv)
            let c = NSLayoutConstraint.init(item: self, attribute: .centerY, relatedBy: .equal, toItem: superv, attribute: .bottom, multiplier: 1, constant: -40)
            c.isActive = true
            diameterConstraint = self.constrainHeight(superv.frame.height * 2.1)
            //
            let panGesture = UIPanGestureRecognizer(target: self, action: #selector(handlePan(_:)))
            panGesture.delegate = gestureDelegate
            self.superview?.addGestureRecognizer(panGesture)
        }
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        self.layer.cornerRadius = self.frame.width / 2
    }

}


class ViewController: UIViewController, UIGestureRecognizerDelegate, UICircleMaskDelegate {

    override var prefersStatusBarHidden: Bool {
        get {
            return true
        }
    }

    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
        return true
    }

    func circleMaskCompletion() {
//        print("nana")
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.backgroundColor = UIColor.init(red: 48/255, green: 242/255, blue: 194/255, alpha: 1)
        self.view.clipsToBounds = true

        let tap = UITapGestureRecognizer(target: self, action: #selector(handleTap))
        tap.delegate = self
        self.view.addGestureRecognizer(tap)

        let circleMask = UICircleMask(gestureDelegate: self)
        circleMask.delegate = self
        self.view.mask = circleMask

    }

    func handleTap() {
        let num = Int(5 + drand48() * 10)
        (1 ... num).forEach { (_) in
            addView()
        }
    }

    func addView() {

        var image: UIImageView!
        let dd = drand48()
        if dd < 0.5 {
            image = UIImageView(image: #imageLiteral(resourceName: "heart1"))
        } else {
            image = UIImageView(image: #imageLiteral(resourceName: "heart2"))
        }

        image.isUserInteractionEnabled = false
        image.contentMode = .scaleAspectFit
        let dim: CGFloat = 20 + CGFloat(10 * drand48())
        image.constrainHeight(dim)
        image.constrainWidth(dim)

        let animation = CAKeyframeAnimation(keyPath: "position")
        let duration = Double(1.5 * self.view.frame.width / CGFloat((60 + drand48() * 40))) // duration = way / speed
        animation.path = getPath().cgPath
        animation.duration = duration
        animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseOut)
        animation.fillMode = kCAFillModeForwards
        animation.isRemovedOnCompletion = false
        image.layer.add(animation, forKey: nil)

        DispatchQueue.global().asyncAfter(deadline: DispatchTime.now() + duration + 1) {
            DispatchQueue.main.async {
                image.removeFromSuperview()
            }
        }

        if drand48() < 0.3 {
            UIView.animate(withDuration: 0.2 + 0.1 * drand48() , delay: TimeInterval(drand48() * 1), options: [.curveEaseOut, .repeat, .autoreverse], animations: {
                image.transform = CGAffineTransform.init(scaleX: 1.5, y: 1.5)
            }, completion: nil)
        }

        self.view.addSubview(image)
        self.view.sendSubview(toBack: image)

    }


    func getPath() -> UIBezierPath {

        let path = UIBezierPath()

        let startPoint = CGPoint.init(x: -30, y: self.view.frame.height / 2)
        path.move(to: startPoint)

        let r = CGFloat(400 * drand48())
        let cp1 = CGPoint.init(x: self.view.frame.width * 0.33, y: self.view.frame.height * 0.25 - r)
        let cp2 = CGPoint.init(x: self.view.frame.width * 0.66, y: self.view.frame.height * 0.75 + r)
        let endPoint = CGPoint.init(x: self.view.frame.width + 30, y: self.view.frame.height / 2)

        path.addCurve(to: endPoint, controlPoint1: cp1, controlPoint2: cp2)

        return path

    }

}


extension UIView {

    func turnOffMaskResizing() {
        self.translatesAutoresizingMaskIntoConstraints = false
    }


    @discardableResult
    func makeSquare() -> NSLayoutConstraint {
        self.turnOffMaskResizing()
        let constraint = NSLayoutConstraint(item: self, attribute: NSLayoutAttribute.width, relatedBy: NSLayoutRelation.equal, toItem: self, attribute: NSLayoutAttribute.height, multiplier: 1.0, constant: 0)
        NSLayoutConstraint.activate([constraint])
        return constraint
    }


    @discardableResult
    func centerHorizontallyTo(_ toItem: UIView, padding: CGFloat) -> NSLayoutConstraint {
        self.turnOffMaskResizing()
        let constraint = NSLayoutConstraint(item: self, attribute: NSLayoutAttribute.centerX, relatedBy: NSLayoutRelation.equal, toItem: toItem, attribute: NSLayoutAttribute.centerX, multiplier: 1.0, constant: padding)
        NSLayoutConstraint.activate([constraint])
        return constraint
    }


    @discardableResult
    func constrainHeight(_ height: CGFloat, priority: UILayoutPriority = 1000) -> NSLayoutConstraint {
        self.turnOffMaskResizing()
        let constraint = NSLayoutConstraint(item: self, attribute: NSLayoutAttribute.height, relatedBy: NSLayoutRelation.equal, toItem: nil, attribute: NSLayoutAttribute.height, multiplier: 0, constant: height)
        constraint.priority = priority
        NSLayoutConstraint.activate([constraint])
        return constraint
    }


}

Answer 1

你的面具在那里，只是它是你视图大小的 2.1 倍，所以它总是覆盖整个东西，所以你可以看到一切。您的代码中有错误：

if pan.state == .began {
        if delta > 0 {
            panStarted = true
            circle.updateSize(-delta)
        }

.began 永远不会有翻译，所以这段代码永远不会被命中，这意味着你的处理程序中没有其他任何东西被处理。这段代码应该只设置panStarted 标志。

您必须拖动很长的距离才能使蒙版生效，并且当您松开时，它会再次弹回视图大小的 2.1 倍。

通过将圆圈添加为子视图而不是蒙版，您可以很容易地看到这一点。用0.5 替换所有2.1 值会给你这个效果：

所以总而言之，你的掩码没有问题，但周围的代码没有问题。