Rotate UIImageView clockwise

Question

This should be simple, but I\'m having trouble rotating a UIImageView a full 360 degrees, repeated forever.

[UIView animateWithDuration:0.5 delay:0          


        

Answer 1

I encountered the same issue a while ago. I do not remember the reason for that issue, but this is my solution:

/**
 * Incrementally rotated the arrow view by a given angle.
 *
 * @param degrees Angle in degrees.
 * @param duration Duration of the rotation animation.
 */
- (void)rotateArrowViewByAngle:(CGFloat)degrees
                  withDuration:(NSTimeInterval)duration {

    CABasicAnimation *spinAnimation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
    spinAnimation.fromValue = [NSNumber numberWithFloat:self.currentAngle / 180.0 * M_PI];
    spinAnimation.toValue = [NSNumber numberWithFloat:degrees / 180.0 * M_PI];
    spinAnimation.duration = duration;
    spinAnimation.cumulative = YES;
    spinAnimation.additive = YES;
    spinAnimation.removedOnCompletion = NO;
    spinAnimation.delegate = self;
    spinAnimation.fillMode = kCAFillModeForwards;

    [self.arrowView.layer addAnimation:spinAnimation forKey:@"spinAnimation"];

    self.currentAngle = degrees;
}

and then you can use the delegate methods

- (void)animationDidStart:(CAAnimation *)theAnimation
- (void)animationDidStop:(CAAnimation *)theAnimation finished:(BOOL)flag

to rotate keep it rotating. Also, degree and duration parameters can be really high numbers... if this is enough.

UPDATE:
As stated by yinkou,

spinAnimation.repeatCount = HUGE_VALF;     // HUGE_VALF is defined in math.h so import it 

is way better that restarting the animation in the delegate.

PLEASE NOTE:
self.currentAngle is a property remembering the current final rotation.
I needed that to make the view rotate left and right way around.