ios - 如何让我的应用程序忽略特定触摸？

Question

我的 iPad 应用程序需要能够完全消除特定的触摸，即来自手指或触控笔的触摸，不是来自您的手掌的触摸。该 View 启用了多点触控，因此我可以分别分析每个触摸。

我目前可以使用 majorRadius 属性区分这些触摸，但我不确定如何才能消除较大的触摸，即那些大于我决定的阈值的触摸。

let touchThreshold : CGFloat = 21.0

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    for touch in touches {
        if touch.majorRadius > touchThreshold {
            //dismiss the touch(???)
        } else {
            //draw touch on screen
        }
    }
}

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
    for touch in touches {
        if touch.majorRadius > touchThreshold {
            //dismiss the touch(???)
        } else {
            //draw touch on screen
        }
    }
}

Answer 1

如果您只想检测某些类型的触摸，这里有一个可能的解决方案:

选项 1

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    touches.forEach { touch in
        switch touch.type {
        case .direct, .pencil:
            handleTouch(for: touch.majorRadius)
        case .indirect:
            // don't do anything
            return
        }
    }
}

func handleTouch(for size: CGFloat) {
    switch size {
    case _ where size > touchThreshold:
        print("do something")
    default:
        print("do something else")
    }
}

选项 2

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    touches.filter{($0.type == .direct || $0.type == .pencil || $0.type == .stylus) && $0.majorRadius > touchThreshold}.forEach { touch in
        print("do something")
    }
}

更多触摸类型可以阅读here .