How to crossfade between 2 images on iPhone using Core Animation

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CABasicAnimation *crossFade = [CABasicAnimation animationWithKeyPath:@"contents"];
crossFade.duration = 5.0;
crossFade.fromValue = image1.CGImage;
crossFade.toValue = image2.CGImage;
[self.imageView.layer addAnimation:crossFade forKey:@"animateContents"];

Note that the animation is independent of the actual values/contents of the UIImageView. Therefore you'll need to

self.imageView.image = image2;

... to set the final result for your image.

I found this somewhere - it works great.

Swift

UIView.transition(with: imageView, duration: 0.33, options: .transitionCrossDissolve, animations: {
      imageView.image = image
}, completion: nil)

Objc

UIImage * toImage = [UIImage imageNamed:@"image.png"];
[UIView transitionWithView:self.view
                  duration:0.33f
                   options:UIViewAnimationOptionTransitionCrossDissolve
                animations:^{
                    self.imageview.image = toImage;
                } completion:NULL];

extension UIImageView
{
    func mySetImage(image:UIImage)
    {
        guard let currentImage = self.image where currentImage != image else { return }
        let animation = CATransition()
        animation.duration = 0.3
        animation.type = kCATransitionFade
        layer.add(animation, forKey: "ImageFade")
        self.image = image
    }
}