swift - 在覆盖 View 上启用用户交互

Question

我正在 UITableView 顶部创建一个变暗的覆盖层，我想突出显示其中一行。我可以突出显示它，但如何启用用户交互(例如点击单元格)？

func addFullScreenDarkOverlay(){
    let viewDarkOverlay = UIView()
    viewDarkOverlay.alpha = 0.5
    viewDarkOverlay.backgroundColor = .black
    viewDarkOverlay.frame = UIApplication.shared.keyWindow!.frame

    //  add dummy hole (will change it to the frame of the particular cell)
    let holeFrame = CGRect(x: 0, y: 0, width: viewDarkOverlay.frame.width/2, height: viewDarkOverlay.frame.height/2)

    // Do any additional setup after loading the view.
    let path = CGMutablePath()
    // Dark background
    path.addRect(CGRect(x: 0, y: 0, width: viewDarkOverlay.frame.width, height: viewDarkOverlay.frame.height))
    // White/spotlight path
    path.addRect(holeFrame)

    let maskLayer = CAShapeLayer()
    maskLayer.backgroundColor = UIColor.black.cgColor
    maskLayer.path = path;
    maskLayer.fillRule = kCAFillRuleEvenOdd

    viewDarkOverlay.layer.mask = maskLayer
    viewDarkOverlay.clipsToBounds = true


    UIApplication.shared.keyWindow!.addSubview(viewDarkOverlay)


}

Answer 1

基本上，您可以禁用 mask View 的用户交互，这会将所有触摸事件传递到下面的 View ...但是，如果您只是希望突出显示的区域难以处理(即单元格)，您可以可以创建一个自定义的 UIView 子类，重写 hitTest 方法，如下所示:

import UIKit

class MaskView: UIView {

    var hitableArea: CGRect {
        return CGRect(x: 0, y: 0, width: bounds.width * 0.5, height: bounds.height * 0.5)
    }

    override init(frame: CGRect) {
        super.init(frame: frame)
        installMaskLayer()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        installMaskLayer()
    }

    private func installMaskLayer() {

        backgroundColor = UIColor.black.withAlphaComponent(0.5)

        let path = CGMutablePath()
        // Dark background
        path.addRect(bounds)
        // White/spotlight path
        path.addRect(hitableArea)

        let maskLayer = CAShapeLayer()
        maskLayer.backgroundColor = UIColor.black.cgColor
        maskLayer.path = path;
        maskLayer.fillRule = CAShapeLayerFillRule.evenOdd

        layer.mask = maskLayer
    }

    override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
        if (!self.isUserInteractionEnabled || self.isHidden || self.alpha <= 0.01) {
            return nil;
        }

        if (hitableArea.contains(point)) {
            return nil
        }

        return self
    }
}

只需创建此自定义 View 并将其添加到您的窗口中，现在您只能触摸该单元格。