InfiniteRotation.m

BOOL animating;
BOOL animationPending;
BOOL animationComplete;

- (void)rotateWithOptions:(UIViewAnimationOptions)options {
    NSTimeInterval fullRotationInterval = 4.0;
    [UIView animateWithDuration:fullRotationInterval/4.0 delay:0 options:options animations:^{
        self.musicIconImageView.transform = CGAffineTransformRotate(self.musicIconImageView.transform, M_PI_2);
    } completion:^(BOOL finished) {
        if (animating) {
            [self rotateWithOptions:UIViewAnimationOptionCurveLinear];
        } else if (animationPending) {
            animationPending = NO;
            animating = YES;
            [self rotateWithOptions:UIViewAnimationOptionBeginFromCurrentState];
        } else if ((options & UIViewAnimationOptionCurveEaseOut) == 0) {
            // Last spin
            [self rotateWithOptions:UIViewAnimationOptionBeginFromCurrentState | UIViewAnimationOptionCurveEaseOut];
        } else {
            animationComplete = NO;
        }
    }];
}

- (void)startRotation {
    animationComplete = NO;
    if (!animating) {
        if (animationComplete) {
            animationPending = YES;
        } else {
            animating = YES;
            [self rotateWithOptions:UIViewAnimationOptionCurveEaseIn];
        }
    }
}

- (void)stopRotation {
    animating = NO;
    animationComplete = YES;
}