You can do that in super elegant way with animator
(reducing UIVisualEffectView alpha will not affect blur intensity, so we must use animator)
Usage as simple as:
let blurEffectView = BlurEffectView()
view.addSubview(blurEffectView)
BlurEffectView realisation:
class BlurEffectView: UIVisualEffectView {
var animator = UIViewPropertyAnimator(duration: 1, curve: .linear)
override func didMoveToSuperview() {
guard let superview = superview else { return }
backgroundColor = .clear
frame = superview.bounds //Or setup constraints instead
setupBlur()
}
private func setupBlur() {
animator.stopAnimation(true)
effect = nil
animator.addAnimations { [weak self] in
self?.effect = UIBlurEffect(style: .dark)
}
animator.fractionComplete = 0.1 //This is your blur intensity in range 0 - 1
}
deinit {
animator.stopAnimation(true)
}
}