Fade/Dissolve When Changing Uiimageview'S Image

Fade/dissolve when changing UIImageView's image

Edit: there is a better solution from @algal below.

Another way to do this is by using predefined CAAnimation transitions:

CATransition *transition = [CATransition animation];
transition.duration = 0.25;
transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
transition.type = kCATransitionFade;
transition.delegate = self;
[self.view.layer addAnimation:transition forKey:nil];
view1.hidden = YES;
view2.hidden = NO;

See the View Transitions example project from Apple: https://developer.apple.com/library/content/samplecode/ViewTransitions/Introduction/Intro.html#//apple_ref/doc/uid/DTS40007411

Fade/dissolve when changing UIImageView's image with percentage

This Extension works for me:

extension UIImage {
    static func mergeImage(imageA: UIImage, imageB:UIImage, percentage: CGFloat) -> UIImage{

        UIGraphicsBeginImageContextWithOptions(imageA.size, false, 0.0)

        imageA.draw(at: CGPoint(x: 0, y: 0), blendMode: .normal, alpha: 1-percentage)

        imageB.draw(at: CGPoint(x: 0, y: 0), blendMode: .normal, alpha: percentage)

        let mergedImage = UIGraphicsGetImageFromCurrentImageContext();

        UIGraphicsEndImageContext();

        return mergedImage!;
    }
}

White screen when attempting to fade between images in UIImageView

AutoLayout not calculated yet when in viewDidLoad

You can set frame when layout changed in viewDidLayoutSubviews.
Try this

class ViewController: UIViewController {

    var bckgImageView = UIImageView(image: UIImage(named: "one"))

    override func viewDidLoad() {
        super.viewDidLoad()

        bckgImageView.frame = self.view.frame
        self.view.addSubview(bckgImageView)

        animateBackground()

    }

    func animateBackground() {

        UIView.transition(with: self.view,
                          duration: 5,
                          options: .transitionCrossDissolve,
                          animations: { self.bckgImageView.image = UIImage(named: "two") },
                          completion: nil)

    }

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        bckgImageView.frame = self.view.frame
    }

}

Fade in/out Image in UIIamgeView happens with no duration

Try to start the animation in the viewDidAppear delegate. Think thats the problem.

Fade In UIImageView

The image needs to be visible all the time while you're fading it in. You are animating the alpha property on a hidden image, and then showing it at the end. Correct would be:

Image.hidden = NO;
[UIView animateWithDuration:0.5 
                      delay:1.0 
                    options:UIViewAnimationOptionCurveEaseIn 
                 animations:^{ Image.alpha = 1; }
                 completion:^(BOOL finished){}
];

How to animate the change of image in an UIImageView?

I am not sure if you can animate UIViews with fade effect as it seems all supported view transitions are defined in UIViewAnimationTransition enumeration. Fading effect can be achieved using CoreAnimation. Sample example for this approach:

#import 
...
imageView.image = [UIImage imageNamed:(i % 2) ? @"3.jpg" : @"4.jpg"];

CATransition *transition = [CATransition animation];
transition.duration = 1.0f;
transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
transition.type = kCATransitionFade;

[imageView.layer addAnimation:transition forKey:nil];

UIImageView change picture with fade effect

You can do this by using UIView's + transitionWithView:duration:options:animations:completion: method.

[UIView transitionWithView:yourImageView duration:7.0f options:UIViewAnimationOptionTransitionCrossDissolve animations:^{
       yourImageView.image = newImage;
    } completion:nil];