Pinch Zoom into UIImageView inside a UITableViewCell - uiscrollview

Question

I am creating a tableview where I will have an UIImageViewinside a UITableViewCell that I would like to allow the user to zoom into. I have been able to create this effect inside a UIScrollView but have struggled to get it right for zooming into a single UITableViewCell.
At the bottom I have included the code that has worked for me for the UIScrollView. The challenge starts with what to return for the viewForZoomingInScrollView. If I try to give this method the UIImageView from the cell It throws an errors as it appears the viewForZoomingInScrollView is called before the table is loaded thus it can not find the cell I am referencing. If I pass the entire view itself self.view I can scroll but the entire tableview is zoomed (where I would like to zoom just the UIImageView inside the cell) and when I release the zoom I get an error Terminating app due to uncaught exception 'CALayerInvalidGeometry', reason: 'CALayer bounds contains NaN: [nan nan; 375 667] which is clearly not the correct path to take.
Any help or guidance here would be appreciated.
- (UIView*)viewForZoomingInScrollView:(UIScrollView *)scrollView {
return self.imageView;
}
- (void)scrollViewDidZoom:(UIScrollView *)scrollView {
[self centerScrollViewContents];
}
- (void)centerScrollViewContents {
CGSize boundsSize = zoomTable.bounds.size;
CGRect contentsFrame = self.imageView.frame;
if (contentsFrame.size.width < boundsSize.width) {
contentsFrame.origin.x = (boundsSize.width - contentsFrame.size.width) / 2.0f;
} else {
contentsFrame.origin.x = 0.0f;
}
if (contentsFrame.size.height < boundsSize.height) {
contentsFrame.origin.y = (boundsSize.height - contentsFrame.size.height) / 2.0f;
} else {
contentsFrame.origin.y = 0.0f;
}
self.imageView.frame = contentsFrame;
}

Answer 1

It sounds to me as though you want something like what Facebook or Twitter have, where you tap on an image and it zooms to fit the screen.
What you need to do is to consider that as a navigational step -- i.e. conceptually similar to what happens if you select a row in a standard table view and it pushes a new view controller onto the navigation controller stack, except that you probably want to present modally using a custom transition.
In the simple case, this would mean adding a tap gesture recogniser to the cell's image view; for the full effect you would add a pinch gesture recogniser to make an interactive transition.
I'd recommend watching the following WWDC videos:
2013 Session 218 "Custom Transitions Using View Controllers"
2014 Session 214 "View Controller Advancements in iOS 8"
2014 Session 228 "A Look Inside Presentation Controllers"

Answer 2

From your question What I understand is that you wanted to implement the functionality of Zoom in and Zoom out for ImageView. You first implemented that in a sample where you had a ScrollView Inside a ViewController and then ImageView inside that ScrollView. Things worked for you as expected. But then when you wanted the same functionality inside the TableViewCell, things didn't work for you.
So, I am suggesting you to use a View inside ScrollView as a ZoomView, and that ZoomView should have the ImageView as subview. And return that ZoomView in the method:
- (UIView*)viewForZoomingInScrollView:(UIScrollView *)scrollView { return self.ZoomView; }