挂在超级视图边缘的UIView将触摸手势事件发送到不相关的底层视图

我们可以实施 hitTest() 以允许使用视图边界之外的触摸。

但是,我们需要 检查 对于被触摸的景色。

所以,你说你有一个子视图(我称之为 tipView )包含一个按钮和一个分段控件作为子视图,并且您正在添加 tipView 作为的子视图 UITextView 已定位 外部 文本视图的边界。

例如:

class ToolTipTextView: UITextView {

    var tipView: UIView!
    var btn: UIButton!
    var seg: UISegmentedControl!

    override init(frame: CGRect, textContainer: NSTextContainer?) {
        super.init(frame: frame, textContainer: textContainer)
        commonInit()
    }
    required init?(coder: NSCoder) {
        super.init(coder: coder)
        commonInit()
    }
    
    func commonInit(){
        
        // we need to see the view outside our bounds
        self.clipsToBounds = false
        
        tipView = UIView()
        tipView.backgroundColor = UIColor(white: 0.95, alpha: 1.0)

        btn = UIButton()
        btn.setTitle("Tap Me", for: [])
        btn.setTitleColor(.white, for: .normal)
        btn.setTitleColor(.lightGray, for: .highlighted)
        btn.backgroundColor = .systemBlue
        
        seg = UISegmentedControl(items: ["One", "Two", "Three"])
        
        [tipView, btn, seg].forEach { v in
            v.translatesAutoresizingMaskIntoConstraints = false
        }

        tipView.addSubview(btn)
        tipView.addSubview(seg)
        self.addSubview(tipView)

        NSLayoutConstraint.activate([
            // button at top of tipView, centerX
            btn.topAnchor.constraint(equalTo: tipView.topAnchor, constant: 4.0),
            btn.centerXAnchor.constraint(equalTo: tipView.centerXAnchor),
            
            // seg control below button
            seg.topAnchor.constraint(equalTo: btn.bottomAnchor, constant: 4.0),
            seg.bottomAnchor.constraint(equalTo: tipView.bottomAnchor, constant: -4.0),
            seg.leadingAnchor.constraint(equalTo: tipView.leadingAnchor, constant: 4.0),
            seg.trailingAnchor.constraint(equalTo: tipView.trailingAnchor, constant: -4.0),

            // tipView above self, centerX
            tipView.bottomAnchor.constraint(equalTo: self.topAnchor, constant: -4.0),
            tipView.centerXAnchor.constraint(equalTo: self.centerXAnchor),
        ])
        
        // targets for btn and seg
        btn.addTarget(self, action: #selector(btnTapped(_:)), for: .touchUpInside)
        seg.addTarget(self, action: #selector(segSelected(_:)), for: .valueChanged)
        
    }
    
    @objc func btnTapped(_ sender: Any?) {
        let str = self.text ?? ""
        self.text = str + " Button Tapped! "
    }
    @objc func segSelected(_ sender: Any?) {
        guard let ctrl = sender as? UISegmentedControl,
              let t = ctrl.titleForSegment(at: ctrl.selectedSegmentIndex)
        else { return }
        let str = self.text ?? ""
        self.text = str + " Segment \(t) Selected! "
    }
    
}

class TipTestVC: UIViewController {
    
    let myView = ToolTipTextView()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        myView.translatesAutoresizingMaskIntoConstraints = false
        
        view.addSubview(myView)
        
        let g = view.safeAreaLayoutGuide
        NSLayoutConstraint.activate([
            myView.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
            myView.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
            myView.heightAnchor.constraint(equalToConstant: 160.0),
            myView.centerYAnchor.constraint(equalTo: g.centerYAnchor),
        ])
        
        myView.font = .systemFont(ofSize: 20.0, weight: .light)
        myView.text = "This is text in the text view."

        // so we can see the text view frame
        myView.backgroundColor = .green
        
    }
    
}

并且在运行时会是这样的:

假设这接近你想要的。。。

正如您所看到的,您无法点击按钮或分段控件。

因此,我们需要添加 hitTest() 按照我们的习惯 ToolTipTextView 类别:

override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {

    // convert the touch to the tipView coordinate space
    let cvtPoint = self.convert(point, to: tipView)

    if btn.frame.contains(cvtPoint) {
        return btn
    }
    
    if seg.frame.contains(cvtPoint) {
        return seg
    }

    return super.hitTest(point, with: event)

}

因为视图、按钮和seg控件 不 在视图的边界内,点击按钮将产生一个触摸点 相对于文本视图 --点击按钮可能会告诉你这一点: (167.0, -59.5) 。

因此,我们将该点转换为 tipView 坐标空间,并查看它是否包含在按钮或seg控件的框架中。如果是这样的话,我们就返回这一观点。

如果没有,我们打电话 super 让UIKit处理触摸。。。如果触摸在内部则激活文本视图,或者允许触摸到达屏幕上的某个其他UI元素。