How to Rotate a Circular Image in ios Continuously? [duplicate]

Question

I'm trying to rotate a UIImageView 360 degrees, and have looked at several tutorials online. I could get none of them working, without the UIView either stopping, or jumping to a new position.

• How can I achieve this?

The latest thing I've tried is:

[UIView animateWithDuration:1.0
                      delay:0.0
                    options:0
                 animations:^{
                     imageToMove.transform = CGAffineTransformMakeRotation(M_PI);
                 } 
                 completion:^(BOOL finished){
                     NSLog(@"Done!");
                 }];

But if I use 2*pi, it doesn't move at all (since it's the same position). If I try to do just pi (180 degrees), it works, but if I call the method again, it rotates backwards.

EDIT:

[UIView animateWithDuration:1.0
                      delay:0.0
                    options:0
                 animations:^{
                     [UIView setAnimationRepeatCount:HUGE_VALF];
                     [UIView setAnimationBeginsFromCurrentState:YES];
                     imageToMove.transform = CGAffineTransformMakeRotation(M_PI);
                 } 
                 completion:^(BOOL finished){
                     NSLog(@"Done!");
                 }];

doesn't work either. It goes to 180 degrees, pauses for a split second, then resets back to 0 degrees before it starts again.

Answer 1

Found a method (I modified it a bit) that worked perfectly for me: iphone UIImageView rotation

#import <QuartzCore/QuartzCore.h>

- (void) runSpinAnimationOnView:(UIView*)view duration:(CGFloat)duration rotations:(CGFloat)rotations repeat:(float)repeat {
    CABasicAnimation* rotationAnimation;
    rotationAnimation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
    rotationAnimation.toValue = [NSNumber numberWithFloat: M_PI * 2.0 /* full rotation*/ * rotations * duration ];
    rotationAnimation.duration = duration;
    rotationAnimation.cumulative = YES;
    rotationAnimation.repeatCount = repeat ? HUGE_VALF : 0;

    [view.layer addAnimation:rotationAnimation forKey:@"rotationAnimation"];
}

Answer 2

Kudos to Richard J. Ross III for the idea, but I found that his code wasn't quite what I needed. The default for options, I believe, is to give you UIViewAnimationOptionCurveEaseInOut, which doesn't look right in a continuous animation. Also, I added a check so that I could stop my animation at an even quarter turn if I needed (not infinite, but of indefinite duration), and made the acceleration ramp up during the first 90 degrees, and decelerate during the last 90 degrees (after a stop has been requested):

// an ivar for your class:
BOOL animating;

- (void)spinWithOptions:(UIViewAnimationOptions)options {
   // this spin completes 360 degrees every 2 seconds
   [UIView animateWithDuration:0.5
                         delay:0
                       options:options
                    animations:^{
                       self.imageToMove.transform = CGAffineTransformRotate(imageToMove.transform, M_PI / 2);
                    }
                    completion:^(BOOL finished) {
                       if (finished) {
                          if (animating) {
                             // if flag still set, keep spinning with constant speed
                             [self spinWithOptions: UIViewAnimationOptionCurveLinear];
                          } else if (options != UIViewAnimationOptionCurveEaseOut) {
                             // one last spin, with deceleration
                             [self spinWithOptions: UIViewAnimationOptionCurveEaseOut];
                          }
                       }
                    }];
}

- (void)startSpin {
   if (!animating) {
      animating = YES;
      [self spinWithOptions: UIViewAnimationOptionCurveEaseIn];
   }
}

- (void)stopSpin {
    // set the flag to stop spinning after one last 90 degree increment
    animating = NO;
}

Update

I added the ability to handle requests to start spinning again (startSpin), while the previous spin is winding down (completing). Sample project here on Github.