UIImage view animate from one image to the next - iphone

Question

I want to smothly animate an image in an UIImageView to turn into the next one within one second like UIModalTransitionStyleCrossDissolve does.
Currently, I've got an UIImageView * called "imageView" and a function which is called "imageForState" which returns me a UIImage * for the correct image.
So what I want to do is to animate the image A smoothly into image B if there is one.
Currently, my function is like that:
- (UIImage *) imageForState{
NSLog(#"state: %d", [save state]);
switch ([save state]) {
case 0:
case 1:
return [UIImage imageNamed:#"Sakuya_Debug.PNG"];
case 2:
return [UIImage imageNamed:#"Sakuya_2_Debug.PNG"];
default:
return NULL;
//Never called
}
}
-(void) tap{
[imageView setAnimationImages:[NSArray arrayWithObjects:[imageView image], [self imageForState], nil]];
imageView.animationDuration = 2.0;
[imageView startAnimating];
save.state++;
}
My problem is, that 1.) the animation goes on forever (when I set imageView.animationRepeatCount to 1, I end up at the first image again) and b.) the animation is not smooth; just like I would have used "setImage";
What am I doing wrong?

Answer 1

I suggest doing it with two imageViews and an animation block. In the following example I assume two square images with a siza of 100px. If you add the two imageViews as subviews make sure that imageB is added after imageA so it covers it.
Init the imageViews:
UIImageView *imageA = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"Sakuya_Debug.PNG"]];
UIImageView *imageB = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"Sakuya_2_Debug.PNG"]];
// hide the second image
imageB.alpha = 0.0;
// put the image with the same size at same position
imageA.frame = CGRectMake(0.0, 0.0, 100.0, 100.0);
imageB.frame = imageA.frame;
Blend method:
- (void)crossDissolveImageAtoB
{
[UIView animateWithDuration:1.0
animations:^{
imageB.alpha = 1.0;
}
completion:^(BOOL finished){
// do something after the animation finished,
// maybe releasing imageA if it's not used anymore...
}];
}