You can animate the grow and decrease size of the image view using the following code
[UIView animateWithDuration:2.0 animations:^{
self.imageView.transform = CGAffineTransformMakeScale(0.5, 0.5);
}
completion:^(BOOL finished){
[UIView animateWithDuration:2.0 animations:^{
self.imageView.transform = CGAffineTransformMakeScale(1, 1);
}];
}];
This will make the imageview decrease in size initially and when animation is over it will get back to its original size with an animation.