rotate a UIView around its center but several times

Question

I\'m trying to rotate some UIView around its center, so the simple code goes something like (in pseudocode):

[UIView beginAnimations:@\"crazyRo         


        

Answer 1

As Brad Larson indicated, you can do this with a CAKeyframeAnimation. For instance,

CAKeyframeAnimation *rotationAnimation;
rotationAnimation = 
   [CAKeyframeAnimation animationWithKeyPath:@"transform.rotation.z"];

rotationAnimation.values = [NSArray arrayWithObjects:
                            [NSNumber numberWithFloat:0.0 * M_PI], 
                            [NSNumber numberWithFloat:0.75 * M_PI], 
                            [NSNumber numberWithFloat:1.5 * M_PI], 
                            [NSNumber numberWithFloat:2.0 * M_PI], nil]; 
rotationAnimation.calculationMode = kCAAnimationPaced;
rotationAnimation.removedOnCompletion = NO;
rotationAnimation.fillMode = kCAFillModeForwards;
rotationAnimation.timingFunction = 
   [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
rotationAnimation.duration = 10.0;

CALayer *layer = [viewToSpin layer];
[layer addAnimation:rotationAnimation forKey:@"rotationAnimation"];

You can control the duration of the total animation with the rotationAnimation.duration property, and the acceleration and deceleration (and calculation of steps in between) with the rotationAnimation.timingFunction property.

Answer 2

Getting a continuous spinning effect is a little tricky, but I describe a means to do it here. Yes, Core Animation seems to optimize transforms to the closest ending position within the unit circle. The method I describe there chains a few half-rotation animations together to make full rotations, although you do notice a slight stutter in the handoff from one animation to the next.

Perhaps a CAKeyframeAnimation constructed with these half-rotation values would be the right way to go. Then you could also control acceleration and deceleration.

Answer 3

CABasicAnimation* animation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
animation.fromValue = [NSNumber numberWithFloat:0.0f];
animation.toValue = [NSNumber numberWithFloat: 2*M_PI];
animation.duration = 8.0f;
animation.repeatCount = INFINITY;
[self.myView.layer addAnimation:animation forKey:@"SpinAnimation"];

Answer 4

You can use the following animation on your UIView's layer property. I've tested it.

Objective-C

UIView *viewToSpin = ...;    
CABasicAnimation* spinAnimation = [CABasicAnimation
                                  animationWithKeyPath:@"transform.rotation"];
spinAnimation.toValue = [NSNumber numberWithFloat:5*2*M_PI];
[viewToSpin.layer addAnimation:spinAnimation forKey:@"spinAnimation"];

Swift 5.0

let viewToSpin = UIView() // However you have initialized your view
let spinAnimation = CABasicAnimation.init(keyPath: "transform.rotation")
spinAnimation.toValue = NSNumber(value: 5.0 * 2.0 * Float.pi)
viewToSpin.layer.add(spinAnimation, forKey: "spinAnimation")