UIScrollView内容不缩放

Question

我有UIImageView里面的UIScrollview，当我尝试捏和缩放，图像跳下来，右（我认为坐标0,0而不是居中），但保持相同的大小，并在同一个地方，直到我停止捏，然后它回到它以前居中的自己。

我得到NSLog在缩放时打印出zoomScale，并且只是保持打印0.5，直到我放开，然后打印1.0一次。

我真的很茫然，所有关于这个的教程看起来非常简单和容易，我不知道我要去哪里错了。

备注： scrollView和ImageView都在storyboard中，连接到插座。它们所在的viewController是一个实现了viewForZoomingInScrollView：的UIScrollView委托。 minimumScale是1.0，maximumScale是4.0，尽管这些数字似乎没有任何影响。

Answer 1

将这个代码在viewDidLoad中

yourScroll.bouncesZoom = YES; 
yourScroll.delegate = self; 
yourScroll.clipsToBounds = YES; 

UITapGestureRecognizer *twoFingerTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTwoFingerTap:)]; 

[twoFingerTap setNumberOfTouchesRequired:2]; 

[yourImageView addGestureRecognizer:twoFingerTap]; 

float minimumScale = 1.0;//This is the minimum scale, set it to whatever you want. 1.0 = default 

yourScroll.maximumZoomScale = 4.0; 
yourScroll.minimumZoomScale = minimumScale; 
yourScroll.zoomScale = minimumScale; 
[yourScroll setContentMode:UIViewContentModeScaleAspectFit]; 
[yourScroll sizeToFit]; 
[yourScroll setContentSize:CGSizeMake(yourImageView.frame.size.width, yourImageView.frame.size.height)]; 

添加滚动视图的委托方法和手势

#pragma mark UIScrollViewDelegate methods 

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

    return yourImageView; 
} 

#pragma mark TapDetectingImageViewDelegate methods 

- (void)scrollViewDidZoom:(UIScrollView *)aScrollView { 
    CGFloat offsetX = (yourScroll.bounds.size.width > yourScroll.contentSize.width)? 
    (yourScroll.bounds.size.width - yourScroll.contentSize.width) * 0.5 : 0.0; 
    CGFloat offsetY = (yourScroll.bounds.size.height > yourScroll.contentSize.height)? 
    (yourScroll.bounds.size.height - yourScroll.contentSize.height) * 0.5 : 0.0; 
    yourImageView.center = CGPointMake(yourScroll.contentSize.width * 0.5 + offsetX, 
             yourScroll.contentSize.height * 0.5 + offsetY); 
} 


- (void)handleTwoFingerTap:(UIGestureRecognizer *)gestureRecognizer { 
    // two-finger tap zooms out 
    float newScale = [previewScroll zoomScale]/ZOOM_STEP; 
    CGRect zoomRect = [self zoomRectForScale:newScale withCenter:[gestureRecognizer locationInView:gestureRecognizer.view]]; 
    [yourScroll zoomToRect:zoomRect animated:YES]; 
} 

#pragma mark Utility methods 

- (CGRect)zoomRectForScale:(float)scale withCenter:(CGPoint)center { 

    CGRect zoomRect; 

    // the zoom rect is in the content view's coordinates. 
    // At a zoom scale of 1.0, it would be the size of the imageScrollView's bounds. 
    // As the zoom scale decreases, so more content is visible, the size of the rect grows. 
    zoomRect.size.height = [previewScroll frame].size.height/scale; 
    zoomRect.size.width = [previewScroll frame].size.width/scale; 

    // choose an origin so as to get the right center. 
    zoomRect.origin.x = center.x - (zoomRect.size.width/2.0); 
    zoomRect.origin.y = center.y - (zoomRect.size.height/2.0); 

    return zoomRect; 
}