Question

I want to rotate a UIImageView, and I am using this code:

-(IBAction)rotateImageView:(id)sender{
 photoView.transform = CGAffineTransformMakeRotation(M_PI); //rotation in radians
}

The code works. when I press the button, the image rotates 180 degrees, but if I press it again it doesn’t rotate back to its original position, but it stays still. why??

Answer 1

Because you are applying the same transform to the view again, without taking into account any existing transform.

Try this:

photoView.transform = CGAffineTransformRotate(photoView.transform,M_PI);