向 UIPangesture 添加边界

Question

我在subview 中有一个UILabel，在UILabel 上有一个panGesture 和pinchGesture。截至目前，我可以将UILabel 移动到所有视图中。我希望这个UILabel 留在subView 的区域内。我将如何做到这一点？

- (void)handlePanGesture:(UIPanGestureRecognizer *)panGesture {
CGPoint translation = [panGesture translationInView:panGesture.view.superview];

if (UIGestureRecognizerStateBegan == panGesture.state ||UIGestureRecognizerStateChanged == panGesture.state) {
    panGesture.view.center = CGPointMake(panGesture.view.center.x + translation.x,
                                         panGesture.view.center.y + translation.y);
    [panGesture setTranslation:CGPointZero inView:self.view];
 }
}

在这一行中，

CGPoint translation = [panGesture translationInView:panGesture.view.superview];

它正在将其设置为 superView，我正在尝试将其设置为我的 subView，但我似乎无法弄清楚。

Answer 1

这是我处理可拖动按钮并将其限制在主视图边界的代码 希望这段代码对你有帮助

 CGPoint translation = [recognizer translationInView:self.view];
    CGRect recognizerFrame = recognizer.view.frame;
    recognizerFrame.origin.x += translation.x;
    recognizerFrame.origin.y += translation.y;

    // Check if UIImageView is completely inside its superView
    if (CGRectContainsRect(self.view.bounds, recognizerFrame)) {
        recognizer.view.frame = recognizerFrame;
    }
    // Else check if UIImageView is vertically and/or horizontally outside of its
    // superView. If yes, then set UImageView's frame accordingly.
    // This is required so that when user pans rapidly then it provides smooth translation.
    else {
        // Check vertically
        if (recognizerFrame.origin.y < self.view.bounds.origin.y) {
            recognizerFrame.origin.y = 0;
        }
        else if (recognizerFrame.origin.y + recognizerFrame.size.height > self.view.bounds.size.height) {
            recognizerFrame.origin.y = self.view.bounds.size.height - recognizerFrame.size.height;
        }

        // Check horizantally
        if (recognizerFrame.origin.x < self.view.bounds.origin.x) {
            recognizerFrame.origin.x = 0;
        }
        else if (recognizerFrame.origin.x + recognizerFrame.size.width > self.view.bounds.size.width) {
            recognizerFrame.origin.x = self.view.bounds.size.width - recognizerFrame.size.width;
        }
    }

    // Reset translation so that on next pan recognition
    // we get correct translation value
    [recognizer setTranslation:CGPointZero inView:self.view];