UIImageView is cut off on right side within PageControl after zooming - ios

Question

my image is cut off on the right side after zooming in. if i don't set the offset with cgrect make, then it is not cut off, but i want my image to be centered on the screen. how can i have my image centered and not cut off the right portion after zooming?
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
self.view.backgroundColor = [UIColor grayColor];
UIScrollView *mainScrollView = [[UIScrollView alloc] initWithFrame:self.view.bounds];
mainScrollView.pagingEnabled = YES;
mainScrollView.showsHorizontalScrollIndicator = NO;
mainScrollView.showsVerticalScrollIndicator = NO;
CGRect innerScrollFrame = mainScrollView.bounds;
for (NSInteger i = 0; i < 2; i++) {
UIImageView *imageForZooming = [[UIImageView alloc] initWithImage:[UIImage imageNamed:[NSString stringWithFormat:#"page%d", i + 1]]];
imageForZooming.tag = VIEW_FOR_ZOOM_TAG;
imageForZooming.frame = CGRectMake(50, 0, imageForZooming.bounds.size.width, imageForZooming.bounds.size.height);
UIScrollView *pageScrollView = [[UIScrollView alloc] initWithFrame:innerScrollFrame];
pageScrollView.minimumZoomScale = 0.5f;
pageScrollView.maximumZoomScale = 1.0f;
pageScrollView.contentSize = imageForZooming.bounds.size;
pageScrollView.delegate = self;
[pageScrollView addSubview:imageForZooming];
[mainScrollView addSubview:pageScrollView];
if (i < 1) {
innerScrollFrame.origin.x += innerScrollFrame.size.width;
}
pageScrollView.zoomScale = 0.5f;
}
mainScrollView.contentSize = CGSizeMake(innerScrollFrame.origin.x + innerScrollFrame.size.width, mainScrollView.bounds.size.height);
[self.view addSubview:mainScrollView];
}
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
return [scrollView viewWithTag:VIEW_FOR_ZOOM_TAG];
}
EDIT: here is my view hierarchy
View
mainScrollView
innerScrollFrame
pageScrollView
imageForZooming
innerScrollFrame
pageScrollView
imageForZooming

Answer 1

For anyone else having the same problem in the future, what I did was add the following UIScrollViewDelegate protocol:
- (void)scrollViewDidZoom:(UIScrollView *)scrollView {
UIView *subView = [scrollView.subviews objectAtIndex:0];
CGFloat offsetX = (scrollView.bounds.size.width > scrollView.contentSize.width) ? (scrollView.bounds.size.width - scrollView.contentSize.width) * 0.5 : 0.0;
CGFloat offsetY = (scrollView.bounds.size.height > scrollView.contentSize.height) ? (scrollView.bounds.size.height - scrollView.contentSize.height) * 0.5 : 0.0;
subView.center = CGPointMake(scrollView.contentSize.width * 0.5 + offsetX,
scrollView.contentSize.height * 0.5 + offsetY);
}
i found the answer here: Center content of UIScrollView when smaller
so that the image would be centered after zooming instead of applying the offset that was initially applied. worked like a charm. now when I zoom, none of my image is cut off on either page control, and I can center the image at the beginning of the view.