UIImage doesn't fade in/out when blur is on

Question

I have UIImage which is blurred like this:

myImageView.image = UIImage(named: imageSet[0])
        let blurEffect = UIBlurEffect(style: UIBlurEffectStyle.Light)
        blurEffectView = UIVisualEffectView(effect: blurEffect)
        blurEffectView?.frame = view.bounds
        myImageView.addSubview(blurEffectView!)

and then I want to fade in new UIImage like this:

UIView.transitionWithView(self.backgroundImageView,
        duration:1.0,
        options: UIViewAnimationOptions.TransitionCrossDissolve,
        animations: { self.myImageView.image = UIImage(named: self.imageSet[randomInt]
        },
        completion: nil)

and the problem is, new image simply appears, rather than fade in. If I disable blur, images fade in and out. What I am doing wrong?

Answer 1

You add your blurEffectView as a subview of myImageView but you can not change alpha or give animation to UIBlurEffect nor UIVisualEffectView. Instead of that, add new UIView with same frame and constraints as your imageView object then add your effects as a subview of a UIView object ;

myImageView.image = UIImage(named: imageSet[0])
let animationView = UIView(frame: myImageView.bounds)
animationView.backgroundColor = .clearColor()
blurEffectView = UIVisualEffectView(effect: UIBlurEffect(style:.Light))
blurEffectView?.frame = animationView.bounds
view.addSubview(animationView)
animationView.addSubview(blurEffectView!)