Question

I’m having a problem with the zoomToRect function. I have a scroll view that contains views. When the user clicks on an view, I launch a zoom into it. It’s working except that when the y position of the frame is higher than 2389, the function zoom to the corresponding frame at 2389 y position.

Here is the code I use :

-(void) launchZoomInAnimationInView:(UIView*) cellView; {
    // Get the rect corresponding to the clicked cell
    CGRect zoomedFrame = [self.zoomScrollView convertRect:cellView.frame fromView:cellView.superview];  

    // Zoom to the rect
    [self.zoomScrollView zoomToRect:zoomedFrame animated:YES];

    // Display for debugging
    [ViewToolkit showFrame:zoomedFrame inView:self.zoomScrollView];
    NSLog (@"Zoom on frame %@ with contentSize %f", NSStringFromCGRect(zoomedFrame), self.zoomScrollView.contentSize.height);
}

The function showframe shows me that the frame I calculated is at a correct position (I display a red rectangle on screen).

The NSLog shows that the content size is high enough :

Zoom on frame {{100, 3021.6}, {230.4, 307.2}} with contentSize 10337.759766.

At the end of the animation, I display the bounds of the scrollView and it gives me {{100, 2389}, {768, 1024}}, instead of {{100, 3021.6}, {768, 1024}}
I really don’t get it. For any value above 2389 I always get a ending frame with 2389 y position. And this value doesn’t change when the contentSize is different.

Note that before launching this function, I didn’t change the zoomScale of the scrollView.

Answer 1

The problem was due to my viewForZoomingInScrollView function which was returning the scrollview itself while it’s supposed to return the child of the scrollView.

See the full answer here : https://devforums.apple.com/message/406487

According to the discussion on Apple forum, it seems there is a bug in Apple API so we should NEVER return the scrollView in viewForZoomingInScrollView.