ios - 拖入自定义分段控件时意外调用cancelTracking

Question

我正在使用 this tutorial 中的自定义分段控件，此外，我希望在滑动/拖动时更改选定的段，所以我添加了这些功能:

override func beginTracking(_ touch: UITouch, with event: UIEvent?) -> Bool {
    super.beginTracking(touch, with: event)
    
    let location = touch.location(in: self)
    lastTouchLocation = location

    return true
}

override func continueTracking(_ touch: UITouch, with event: UIEvent?) -> Bool {
    super.continueTracking(touch, with: event)
    
    let location = touch.location(in: self)
    print(location.x - lastTouchLocation!.x)
    
    let newX = thumbView.frame.origin.x + (location.x - lastTouchLocation!.x)
    if frame.minX <= newX && newX + thumbView.frame.width <= frame.maxX {
        thumbView.frame.origin.x = newX
    }
    lastTouchLocation = location
    
    return true
}

override func endTracking(_ touch: UITouch?, with event: UIEvent?) {
    super.endTracking(touch, with: event)
    
    let location = touch != nil ? touch!.location(in: self) : lastTouchLocation!
    
    var calculatedIndex : Int?
    for (index, item) in labels.enumerated() {
        if item.frame.contains(location) {
            calculatedIndex = index
        }
    }
    
    if calculatedIndex != nil && calculatedIndex != selectedIndex {
        selectedIndex = calculatedIndex!
        sendActions(for: .valueChanged)
    } else {
        displayNewSelectedIndex()
    }
}

我已将控件嵌入到 UIView 容器中，当我将拇指 View 拖动一小段距离时，触摸会以某种方式被取消

这可能是 View 容器的问题，我该如何解决？
感谢您阅读全文。

Answer 1

当我的自定义 UIControl 在表单上时，我最近遇到了这个问题。它在弹出窗口上运行良好，但是当我将相同的控件放在表单上时，它会突然中止横向拖动的能力，似乎没有任何理由。 cancelTracking被调用，但事件没有告诉我原因。我发现这与 iOS13 通过向下拖动来解除 Formsheets 的新方法有关。为了修复它，我将此代码添加到扩展 UIControl 的类中:

override func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
    if gestureRecognizer is UIPanGestureRecognizer {
        return false
    }
    return true
}