UIScrollView 在捏合时自动向下滚动？

Posted 2023-03-16

【中文标题】UIScrollView 在捏合时自动向下滚动？

【英文标题】：UIScrollView automatically scrolls down during pinch in?

【发布时间】：2015-02-25 14:45:29

【问题描述】：

我有 uiscrollview 并向其添加了图像视图。当我捏住滚动视图时，我可以放大，但滚动视图会自动向下滚动一点。所以我无法缩放 uiimageview 的底部。

    UIScrollView *scroll = [[UIScrollView alloc]init];
    scroll.minimumZoomScale = 1.0f;
    scroll.maximumZoomScale = 16.0f;
    scroll.delegate = self;

 [scroll setContentSize:CGSizeMake(scroll.frame.size.width, scroll.frame.size.height+2200)];
scroll.frame = self.view.frame;
[scroll setBackgroundColor:[UIColor brownColor]];
[self.view addSubview:scroll];


UIImageView *img = [[UIImageView alloc]init];
[img setBackgroundColor:[UIColor yellowColor]];
[img setImage:[UIImage imageNamed:@"add_button.jpg"]];
[img setFrame:CGRectMake(0, 100, self.view.frame.size.width, 200)];
[img setContentMode:UIViewContentModeScaleAspectFit];
[scroll addSubview:img];



- (UIView*)viewForZoomingInScrollView:(UIScrollView *)scrollView 

    return [[scrollView subviews] firstObject];

【参考方案1】：

这是我的代码，这可能会有所帮助

   - (void) pinchView:(UIPinchGestureRecognizer *)pinchGestureRecognizer
    
        UIView *view = self.showImgView;
        if (pinchGestureRecognizer.state == UIGestureRecognizerStateBegan || pinchGestureRecognizer.state == UIGestureRecognizerStateChanged) 
            view.transform = CGAffineTransformScale(view.transform, pinchGestureRecognizer.scale, pinchGestureRecognizer.scale);
            pinchGestureRecognizer.scale = 1;
        
        else if (pinchGestureRecognizer.state == UIGestureRecognizerStateEnded) 
            CGRect newFrame = self.showImgView.frame;
            newFrame = [self handleScaleOverflow:newFrame];
            newFrame = [self handleBorderOverflow:newFrame];
            [UIView animateWithDuration:BOUNDCE_DURATION animations:^
                self.showImgView.frame = newFrame;
                self.latestFrame = newFrame;
            ];
        
    

【参考方案2】：

我将假设您使用 UIPinchGestureRecognizer 进行捏合事件...

您要做的是在方法的开头和结尾添加这些“if”语句：

- (void)handlePinch:(UIPinchGestureRecognizer *)sender

    if (sender.state == UIGestureRecognizerStateBegan)
        self.scrollView.enabled = NO;

    // pinch handling here

    if ((sender.state == UIGestureRecognizerStateEnded) || (sender.state == UIGestureRecognizerStateCancelled))
        self.scrollView.enabled = YES;

希望这会有所帮助。

【讨论】：

我正在使用 UIScrollView，它具有默认的捏合手势动作。 - (UIView*)viewForZoomingInScrollView:(UIScrollView *)scrollView return [[scrollView subviews] firstObject];

根据您在 OP 中的描述，我认为您想将 UIPinchGestureRecognizer 应用于 UIImageView，而不是 UIScrollView。

@Tim Kokesh UiscrollView 默认获得了 UIPinchGestureRecognizer 所以我更喜欢使用它。还有如何裁剪出现在裁剪矩形中的主图像。