Show and Fade UIImageView after 2 Seconds

Swift 3 version of @AliSoftware's answer

imageView.isHidden = false
imageView.alpha = 1.0

UIView.animate(withDuration: 0.5, delay: 2.0, options: [], animations: {

            self.imageView.alpha = 0.0

        }) { (finished: Bool) in

            self.imageView.isHidden = true
        }

Use UIView dedicated methods for that.

So imagine you already have your UIImageView ready, already created and added to the main view, but simply hidden. Your method simply need to make it visible, and start an animation 2 seconds later to fade it out, by animating its "alpha" property from 1.0 to 0.0 (during a 0.5s animation):

-(IBAction)popupImage
{
    imageView.hidden = NO;
    imageView.alpha = 1.0f;
    // Then fades it away after 2 seconds (the cross-fade animation will take 0.5s)
    [UIView animateWithDuration:0.5 delay:2.0 options:0 animations:^{
         // Animate the alpha value of your imageView from 1.0 to 0.0 here
         imageView.alpha = 0.0f;
     } completion:^(BOOL finished) {
         // Once the animation is completed and the alpha has gone to 0.0, hide the view for good
         imageView.hidden = YES;
     }];
}

Simple as that!

Swift 2

self.overlay.hidden = false
UIView.animateWithDuration(2, delay: 5, options: UIViewAnimationOptions.TransitionFlipFromTop, animations: {
    self.overlay.alpha = 0
}, completion: { finished in
    self.overlay.hidden = true
})

Swift 3, 4, 5

self.overlay.isHidden = false
UIView.animate(withDuration: 2, delay: 5, options: UIView.AnimationOptions.transitionFlipFromTop, animations: {
    self.overlay.alpha = 0
}, completion: { finished in
    self.overlay.isHidden = true
})

Where overlay is the outlet for my image.