How to rotate the image from original and back to it? - ios

Question

I have try to rotate the image by using CGAffineTransformMakeRotation and CGAffineTransformRotate. I want to rotate the image from it's original and clockwise to the original again(like degree 0 to 360). I need to rotate image like a CD on the player. I did something like this:
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:0.1];
CGAffineTransform transform = CGAffineTransformMakeRotation(1.0);
transform = CGAffineTransformRotate(transform, -180);
ImageView.transform = transform;
[UIView commitAnimations];
it just spin to the degree 180, and if I change it to -300 it will rotate counterclockwise (that not what I need).

Answer 1

the angle of rotation is given better by atan2() suppose A and B are two points on the centerline to which your image is to be rotated then the angle of rotation is
0-atan2((b.x - a.x) ,(b.y -a.y))
Hope this helps

Answer 2

Try this:
-(void)startAnimationWithRevolutions:(float)revPerSecond forTime:(float)time
{
spinWheel.userInteractionEnabled = FALSE;
float totalRevolutions = revPerSecond * time;
[CATransaction begin];
[CATransaction setValue:[NSNumber numberWithFloat:time] forKey:kCATransactionAnimationDuration];
CABasicAnimation* spinAnimation = [CABasicAnimation
animationWithKeyPath:#"transform.rotation"];
CGAffineTransform transform = spinWheel.transform;
float fromAngle = atan2(transform.b, transform.a);
float toAngle = fromAngle + (totalRevolutions*4*M_PI);
spinAnimation.fromValue = [NSNumber numberWithFloat:fromAngle];
spinAnimation.toValue = [NSNumber numberWithFloat:toAngle];
spinAnimation.repeatCount = 0;
spinAnimation.removedOnCompletion = NO;
spinAnimation.delegate = self;
spinAnimation.timingFunction = [CAMediaTimingFunction functionWithName:
kCAMediaTimingFunctionEaseOut];
[spinWheel.layer addAnimation:spinAnimation forKey:#"spinAnimation"];
[CATransaction commit];
}

Answer 3

Use this:
[UIView animateWithDuration:0.1 animations:^{
CGAffineTransform transform = CGAffineTransformMakeRotation(1.0);
transform = CGAffineTransformRotate(transform, -180);
ImageView.transform = transform;
} completion:^(BOOL finished) {
CGAffineTransform transform = CGAffineTransformMakeRotation(0);
transform = CGAffineTransformRotate(transform,0);
ImageView.transform = transform;
}];