Touch Up Inside的全局事件处理程序

Question

我有一个触摸操作,它是调整大小的场景的触发器,其中操作在触摸移动时开始,并且需要以touchesEnded结束.问题是,touchesEnd可能位于不同的UI视图上,因为用户正在拖动手指.如何注册*global"touchesEnded listener？

Answer 1

你应该用一个UIPanGestureRecognizer.每次触发时,请检查state手势识别器.如果UIGestureRecognizerStateBegan是,则首先触摸视图,如果是,UIGestureRecognizerStateChanged那么用户正在移动他的手指,如果是,UIGestureRecognizerStateEnded那么用户已经抬起他的手指.

只要手势在您的视图上开始,即使在离开视图边界后,它也会继续(除非取消),因此您不必担心"使其全局化".

使用以下命令初始化手势识别器:

UIPanGestureRecognizer *dragViewGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handleDragView:)];
dragViewGestureRecognizer.maximumNumberOfTouches = 1;
[yourView addGestureRecognizer:dragViewGestureRecognizer];

然后使用您需要的代码填写以下方法:

- (void)handleDragView:(UIPanGestureRecognizer*)panGestureRecognizer {
    switch (panGestureRecognizer.state) {
        case UIGestureRecognizerStateBegan: {
            //Code when dragging starts
            break;
        } case UIGestureRecognizerStateChanged: {
            //Code while dragging is happening (if needed)
            break;
        } case UIGestureRecognizerStateEnded: {
            //Code when dragging ends
            break;
        }
        default:
            break;
    }
}