How to let a view rotate forever? - iphone

Question

Is there a way to let a view rotate forever, with an specified speed? I need that for an indicator kind of thing. I know there is this weird Lxxxxx00ff constant (don't remember it exactly) that stands for "forever".

Answer 1

You can use HUGE_VAL for floating value (if I remember correctly, repeatCount property for animation is a float).
To setup animation you can create CAAnimation object using +animationWithKeyPath: method:
CABasicAnimation* animation = [CABasicAnimation animationWithKeyPath:#"transform.rotation.z"];
animation.fromValue = [NSNumber numberWithFloat:0.0f];
animation.toValue = [NSNumber numberWithFloat: 2*M_PI];
animation.duration = 3.0f;
animation.repeatCount = HUGE_VAL;
[rotView.layer addAnimation:animation forKey:#"MyAnimation"];
If I remember correctly creating this kind of rotation using just UIView animations is impossible because rotations on 360 degrees (2*M_PI radians) are optimized to no rotation at all.
Edit: Added a Swift version.
let animation = CABasicAnimation(keyPath: "transform.rotation.z")
animation.fromValue = NSNumber(value: 0.0)
animation.toValue = NSNumber(value: 2*Double.pi)
animation.duration = 3.0
animation.repeatCount = Float.greatestFiniteMagnitude
rotView.layer.add(animation, forKey: "MyAnimation")

Answer 2

my solution for this is a bit hacky since it doesn't use core animation but at least it works truly forever and doesn't require you to setup multiple animation steps.
...
// runs at 25 fps
NSTimer* timer = [NSTimer scheduledTimerWithTimeInterval:1.0/25
target:self
selector:#selector(rotate)
userInfo:nil
repeats:YES];
[timer fire];
...
- (void)rotate {
static int rotation = 0;
// assuming one whole rotation per second
rotation += 360.0 / 25.0;
if (rotation > 360.0) {
rotation -= 360.0;
}
animatedView.transform = CGAffineTransformMakeRotation(rotation * M_PI / 180.0);
}

Answer 3

my bet is:
-(void)animationDidStopSelector:... {
[UIView beginAnimations:nil context:NULL];
// you can change next 2 settings to setAnimationRepeatCount and set it to CGFLOAT_MAX
[UIView setAnimationDelegate:self];
[UIView setAnimationDidStopSelector:#selector(animationDidStopSelector:...)];
[UIView setAnimationDuration:...
[view setTransform: CGAffineTransformRotate(CGAffineTransformIdentity, 6.28318531)];
[UIView commitAnimations];
}
//start rotation
[self animationDidStopSelector:...];
ok better bet:
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationRepeatCount: CGFLOAT_MAX];
[UIView setAnimationDuration:2.0f];
[view setTransform: CGAffineTransformMakeRotation(6.28318531)];
[UIView commitAnimations];