Question

当UIScrollView捏缩小超过其最小缩放限制并且即将动画回来时，我正试图收到通知，但我发现它非常困难。有没有办法可以单独使用delegate方法执行此操作，还是需要覆盖UIScrollView's触摸处理？

Answer 1

使用scrollViewDidZoom:并检查是否scrollView.zoomBouncing == YES。然后使用zoomScale确定视图弹跳的方向。

- (void)scrollViewDidZoom:(UIScrollView *)scrollView {
    if (scrollView.zoomBouncing) {
        if (scrollView.zoomScale == scrollView.maximumZoomScale) {
            NSLog(@"Bouncing back from maximum zoom");
        }
        else
        if (scrollView.zoomScale == scrollView.minimumZoomScale) {
            NSLog(@"Bouncing back from minimum zoom");
        }
    }
}

Answer 2

您可以使用UIScrollView的scrollViewDidZoom委托方法来检测它即将动画回来的时刻。在视图被挤压时，您会看到scrollView.zoomScale下方scrollView.minimumZoomScale。然后，只要用户松开手指，scrollViewDidZoom将再次使用scrollView.zoomScale == scrollView.minimumZoomScale，scrollView.zooming == NO来调用{。}}。

捕捉这个时刻很好，但是尝试做任何事情来抢占反弹至最小的ZoomScale动画似乎对我来说真的有些奇怪的副作用。：（

Answer 3

在Swift 4.0中：

func scrollViewDidZoom(_ scrollView: UIScrollView) {
    if scrollView.zoomScale == scrollView.minimumZoomScale
    {
        print("zoomed out")
    }
}

当用户完成缩放并且zoomScale处于最小可能值时，即完全缩小滚动视图时，将精确地调用此方法。

Answer 4

我是用UIPinchGestureRecognizer完成的。

-(void)viewDidLoad{
    UIPinchGestureRecognizer *gestureRecognizer = 
     [[[UIPinchGestureRecognizer alloc] initWithTarget:self 
                                                action:@selector(pinched:)] 
                                                               autorelease];
    gestureRecognizer.delegate=self;
    [self.scrollView addGestureRecognizer:gestureRecognizer];
    //your code
}
-(void)pinched:(UIPinchGestureRecognizer*)gestureRecognizer{
    if(gestureRecognizer.state==UIGestureRecognizerStateEnded){
        //pinch ended
        NSLog(@"scale: %f",scrollView.zoomScale);
    }
}
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
        shouldRecognizeSimultaneouslyWithGestureRecognizer:
                          (UIGestureRecognizer *)otherGestureRecognizer{
    return YES;
}

UIScrollView检测捏拉变焦结束

4 个答案: