Transparent blurred view is not working - ios

Question

I'd like to apply layer on top of ImageView that slightly blurrs it.
I put a view on top of imageView, subclass it as follows:
class BlurredView: UIView {
override func draw(_ rect: CGRect) {
self.backgroundColor = UIColor.clear
let blurEffect = UIBlurEffect(style: UIBlurEffectStyle.extraLight)
let blurEffectView = UIVisualEffectView(effect: blurEffect)
blurEffectView.backgroundColor = UIColor.clear
blurEffectView.frame = self.bounds
blurEffectView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
self.addSubview(blurEffectView)
}
}
The result is quite different from what I expected.
How to customize it to make this blur much lighter, so the picture still shows some details?

Answer 1

As https://stackoverflow.com/users/1387306/chrstpsln mentioned in the comment, this can be achieved by changing the alpha of the UIVisualEffectView.
As a bonus, you can add a fade animation to make the transition feel smoother.
Heres an example of how you can add this effect to any viewController through an extension:
extension UIViewController {
func addBlurEffect() {
let blurEffect = UIBlurEffect(style: .light)
let blurVisualEffectView = UIVisualEffectView(effect: blurEffect)
blurVisualEffectView.frame = UIScreen.main.bounds
blurVisualEffectView.alpha = 0.1
// Bonus animation - Or just set the alpha higher
UIView.animate(withDuration: 0.3) {
blurVisualEffectView.alpha = 0.90
}
view.addSubview(blurVisualEffectView)
}
}
Usage:
let viewController = UIViewController()
viewController.addBlurEffect()

Answer 2

You can't change the blur amount, the only thing you can do is to change the blur effect style:
UIBlurEffectStyle.light
UIBlurEffectStyle.extraLight
UIBlurEffectStyle.dark
Try to change the blur effect alpha. Also, since your image is light, you should use the light style and not the extra light in order to not lose details.
let blurEffect = UIBlurEffect(style: UIBlurEffectStyle.light)
blurEffect.alpha = 0.95