ios - 让 UIScrollView 放弃 UITouch

Question

我有一个 Canvas 比手机屏幕大的绘图应用程序。我想实现用两根手指滚动并用一根手指绘图。到目前为止，我可以使滚动工作得很好，但是当涉及到绘图时，线条开始，然后绘图所在的 View 失去了对触摸的控制，因此只绘制了线条的第一部分。我认为 ScrollView 夺回了控制权。点可以画得很好。

这是我的子类 UIScrollView

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    guard let touches = event?.touches(for: self) else { return }
    if touches.count < 2 {
        self.next?.touchesBegan(touches, with: event)
    } else {
        super.touchesBegan(touches, with: event)
    }
}

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
    guard let touches = event?.touches(for: self) else { return }
    if touches.count < 2 {
        self.next?.touchesEnded(touches, with: event)
    } else {
        super.touchesEnded(touches, with: event)
    }
}

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
    guard let touches = event?.touches(for: self) else { return }
    if touches.count < 2 {
        self.next?.touchesMoved(touches, with: event)
    } else {
        super.touchesMoved(touches, with: event)
    }
}

override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?) {
    guard let touches = event?.touches(for: self) else { return }
    if touches.count < 2 {
        self.next?.touchesCancelled(touches, with: event)
    } else {
        super.touchesCancelled(touches, with: event)
    }
}

override func touchesShouldCancel(in view: UIView) -> Bool {
    if (type(of: view)) == UIScrollView.self {
        return true
    }
    return false
}

Answer 1

您需要将长按手势识别器连接到您的 ScrollerView，设置为最短持续时间 0 秒，同时识别仅 1 次触摸和取消触摸查看选项处于事件状态。

您可以在 Interface Builder 的属性检查器下找到所有这些选项。

请稍微调整容差设置以微调结果。