Sample code showing how to add a CATransition to changing the image on a UIImageView

UIImageView+CATransition.m

UIImage* newImage = [UIImage imageNamed:context];
        
// set up an animation for the transition the content
CATransition *animation = [CATransition animation];
[animation setDuration:0.25];
[animation setType:kCATransitionPush];
[animation setSubtype:kCATransitionFromRight];
[animation setTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]];
        
[[self.contentImageView layer] addAnimation:animation forKey:@"SwitchToView1"];

[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:0.25];
        
self.contentImageView.image = newImage;
        
[UIView commitAnimations];