如果移出CGPoint，则取消触摸

Question

我的UIViewController中心有400x400 RootController（我们称之为ViewB）。在ViewB内，我有少量UIButton（自定义UIButton类，触摸UIResponder方法）。

我可以移动按钮，但当触摸屏离开ViewB时，按钮会取消触摸！

我真正想要的是完全取消触摸并将按钮靠近ViewB的边缘。

Answer 1

试试这个，

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {

    UITouch *touch = [[event allTouches] anyObject];
    ....
    CGRect viewBFrame = ViewB.view.frame;
    CGRect buttonToRect = //calculated button frame
    CGPoint buttonOrigin = buttonToRect.origin;
    CGFloat xMax = CGRectGetWidth(viewBFrame) - CGRectGetWidth(buttonToRect);
    CGFloat yMax = CGRectGetHeight(viewBFrame) - CGRectGetHeight(buttonToRect);
    buttonOrigin.x = MAX(0, buttonOrigin.x);
    buttonOrigin.x = MIN(xMax, buttonOrigin.x);

    buttonOrigin.y = MAX(0, buttonOrigin.y);
    buttonOrigin.y = MIN(yMax, buttonOrigin.y);

    //set buttonToRect to Button

}

注意：假设按钮是ViewB

的子视图