how to spin an image continuously - objective-c

Question

I have an wheel image in .png format, I want to know how can i animate so that it rotates continuously, I searched on stackoverflow and found certain snippets of code which helped me rotate my image but it wouldn't rotate continuously, it would just rotate for a few seconds and stop, the code as follows
the code in viewdidload
UIImageView *imageToMove =
[[UIImageView alloc] initWithImage:[UIImageimageNamed:#"horo_circle.png"]];
[self.view addSubview:imageToMove];
[self rotateImage:imageToMove duration:5.0
curve:UIViewAnimationCurveEaseIn degrees:180];
and the animation
- (void)rotateImage:(UIImageView *)image duration:(NSTimeInterval)duration
curve:(int)curve degrees:(CGFloat)degrees
{
// Setup the animation
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:duration];
[UIView setAnimationCurve:curve];
[UIView setAnimationBeginsFromCurrentState:YES];
// The transform matrix
CGAffineTransform transform =
CGAffineTransformMakeRotation(DEGREES_TO_RADIANS(degrees));
image.transform = transform;
// Commit the changes
[UIView commitAnimations];
}
and the following lines after the import
#define M_PI 3.14159265358979323846264338327950288 /* pi */
#define DEGREES_TO_RADIANS(angle) (angle / 180.0 * M_PI)

Answer 1

You are better of doing this with a CABasicAnimation:
if ([self.spinnerOverlay animationForKey:#"SpinAnimation"] == nil) {
CABasicAnimation* animation = [CABasicAnimation animationWithKeyPath:#"transform.rotation.z"];
animation.fromValue = [NSNumber numberWithFloat:0.0f];
animation.toValue = [NSNumber numberWithFloat: 2*M_PI];
animation.duration = 10.0f;
animation.repeatCount = INFINITY;
[self.spinnerOverlay.layer addAnimation:animation forKey:#"SpinAnimation"];
}
In this code I check whether the animation is all ready set, not need to set it again.
The spinnerOverlay is in your case the UIImageView you want to rotate.
To stop the animation:
[self.spinnerOverlay.layer removeAnimationForKey:#"SpinAnimation"];

Answer 2

The code bellow will spin a UIImageView called iconView continiously until rotate == NO.
The image will always return to its original position.
- (void)performRotationAnimated
{
[UIView animateWithDuration:0.5
delay:0
options:UIViewAnimationOptionCurveLinear
animations:^{
self.iconView.transform = CGAffineTransformMakeRotation(M_PI);
}
completion:^(BOOL finished){
[UIView animateWithDuration:0.5
delay:0
options:UIViewAnimationOptionCurveLinear
animations:^{
self.iconView.transform = CGAffineTransformMakeRotation(0);
}
completion:^(BOOL finished){
if (_rotate) {
[self performRotationAnimated];
}
}];
}];
}
This is a variation on the same theme.
(Total duration: 2 * 0.5 = 1 sec for a spin)
Works like magic!

Answer 3

Here is another way to do it with a timer.
In your viewController.h file, you'll need to declare your timer and image:
#interface ViewController : UIViewController
{
IBOutlet UIImageView *spinningImage;
NSTimer *spinTimer;
}
Next, in your ViewController.m, you add this code and can make the spin go faster by lowering the time interval or by increasing the transform interval.
-(void) viewDidLoad {
spinTimer = [NSTimer scheduledTimerWithTimeInterval:.01 target: self selector:#selector(spinVoid) userInfo:nil repeats:YES];
}
-(void) spinVoid {
spinningImage.transform = CGAffineTransformRotate(spinningImage.transform, 0.001);
}
Hope this helps!

Answer 4

Now that we're at iOS6, please consider switching to block based animations (that are available since iOS 4.0) rather than the classical method. Try this:
[UIView animateWithDuration:duration delay:0.0 options:UIViewAnimationOptionRepeat animations:^{
image.transform = CGAffineTransformMakeRotation(DEGREES_TO_RADIANS(degrees));
} completion:nil];

Answer 5

Using the method you've chosen for animations :
[UIView setAnimationRepeatCount:10000000];
or, you can specify the UIViewAnimationOptionRepeat flag in the blocks method animateWithDuration:delay:options:animations:completion: