A simple view to animate in and out a blurry overlay. Use .blurIn() and .blurOut() to animate the blur. User interaction is passed through when the view is not blurry. NOTE: If you use storyboards, you need to drag out a UIVisualEffectView and set the class. It doesn't work if you drag out a plain old UIView.

BlurryOverlayView.swift

class BlurryOverlayView: UIVisualEffectView {
    private var animator: UIViewPropertyAnimator!
    private var delta: CGFloat = 0 // The amount to change fractionComplete for each tick
    private var target: CGFloat = 0 // The fractionComplete we're animating to
    private(set) var isBlurred = false
    private var displayLink: CADisplayLink!
    
    override init(effect: UIVisualEffect?) {
        super.init(effect: effect)
        setup()
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setup()
    }
    
    // Common init
    private func setup() {
        effect = nil // Starts out with no blur
        isHidden = true // Enables user interaction through the view
        
        // The animation to add an effect
        animator = UIViewPropertyAnimator(duration: 1, curve: .easeInOut) {
            self.effect = UIBlurEffect(style: .light)
        }
        animator.pausesOnCompletion = true // Fixes background bug
        
        // Using a display link to animate animator.fractionComplete
        displayLink = CADisplayLink(target: self, selector: #selector(tick))
        displayLink.isPaused = true
        displayLink.add(to: .main, forMode: .commonModes)
    }
    
    func blurIn(amount: CGFloat = 0.2, duration: TimeInterval = 0.3) {
        guard isBlurred == false else { return }
        
        isHidden = false // Disable user interaction
        
        target = amount
        delta = amount / (60 * CGFloat(duration)) // Assuming 60hz refresh rate
        
        // Start animating fractionComplete
        displayLink.isPaused = false
    }
    
    func blurOut(duration: TimeInterval = 0.3) {
        guard isBlurred else { return }
        
        target = 0
        delta = -1 * animator.fractionComplete / (60 * CGFloat(duration)) // Assuming 60hz refresh rate
        
        // Start animating fractionComplete
        displayLink.isPaused = false
    }
    
    @objc private func tick() {
        animator.fractionComplete += delta
        
        if isBlurred && animator.fractionComplete <= 0 {
            // Done blurring out
            isBlurred = false
            isHidden = true
            displayLink.isPaused = true
        } else if isBlurred == false && animator.fractionComplete >= target {
            // Done blurring in
            isBlurred = true
            displayLink.isPaused = true
        }
    }
}

Thank you for creating such wonderful code! But i have a question about blurOut function. I have one View calling BlurryOverlayView and it called blurOut function after 0.5 seconds calling blurIn. But there was some delay loading UIView, and in this case, BlurryOverlayView is not blurred out. So I called blurOut manually if isBlurred is true, but it doesn't work. Do you have any solution?

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