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import UIKit | |
final class CustomIntensityVisualEffectView: UIVisualEffectView { | |
/// Create visual effect view with given effect and its intensity | |
/// | |
/// - Parameters: | |
/// - effect: visual effect, eg UIBlurEffect(style: .dark) | |
/// - intensity: custom intensity from 0.0 (no effect) to 1.0 (full effect) using linear scale | |
init(effect: UIVisualEffect, intensity: CGFloat) { | |
theEffect = effect | |
customIntensity = intensity | |
super.init(effect: nil) | |
} | |
required init?(coder aDecoder: NSCoder) { nil } | |
deinit { | |
animator?.stopAnimation(true) | |
} | |
override func draw(_ rect: CGRect) { | |
super.draw(rect) | |
effect = nil | |
animator?.stopAnimation(true) | |
animator = UIViewPropertyAnimator(duration: 1, curve: .linear) { [unowned self] in | |
self.effect = theEffect | |
} | |
animator?.fractionComplete = customIntensity | |
} | |
private let theEffect: UIVisualEffect | |
private let customIntensity: CGFloat | |
private var animator: UIViewPropertyAnimator? | |
} |
Hejianghao
commented
Apr 16, 2020
•
@Hejianghao It looks like when UICollectionViewCell
is reused, something strange is going on with UIVisualEffect
. Thie quick fix would be to reconfigure the cell every time it's reused:
class MyCollectionViewCell: UICollectionViewCell {
var imageView: UIImageView!
var effectView: UIVisualEffectView!
override init(frame: CGRect) {
super.init(frame: frame)
self.imageView = UIImageView.init(frame: self.bounds)
self.imageView.image = UIImage.init(named: "test")
self.contentView.addSubview(self.imageView)
setupBlurEffect()
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func prepareForReuse() {
super.prepareForReuse()
setupBlurEffect()
}
private func setupBlurEffect() {
effectView.removeFromSuperview()
let effect = UIBlurEffect(style: .light)
let effectView = CustomIntensityVisualEffectView(effect: effect, intensity: 0.3)
effectView.frame = imageView.bounds
imageView.addSubview(effectView)
self.effectView = effectView
}
}
While it's not an ideal solution, it works perfectly in your case. I checked it with the code you provided and it behaves correctly, without any issues.
Thanks, it works. I think the strange thing is the animator.fractionComplete became 1 automatically, when the cell reused.
Doesn't seem to work on iOS 14 :(
@mmdock I didn't check it on iOS 14 yet. Could you provide more details?
On IOS 14.2 this works on initial load of the app. Whenever you switch to another app or home screen and come back, the effect disappears.
@orakay thanks for reporting. I have updated the gist, and it should now work correctly on iOS 14.2. I am not sure about the performance, though, as it recreates the UIViewPropertyAnimator
every time the view is drawn. However, I used this approach in SwiftUI and didn't notice any performance issues.
@orakay thanks for reporting. I have updated the gist, and it should now work correctly on iOS 14.2. I am not sure about the performance, though, as it recreates the
UIViewPropertyAnimator
every time the view is drawn. However, I used this approach in SwiftUI and didn't notice any performance issues.
Thanks for such a quick solution. It works without any performance issue.
cool
great
ios 14.5 from background - effect reset
In order to solve the foreground/background issues try setting animator?.pausesOnCompletion = true
inside func draw(_ rect: CGRect)
after animator = UIViewPropertyAnimator(.....
Just as a heads up, this code has trouble with UITests.
Setting fractionComplete
on an animator and not stopping the animation essentially indicates to the test runner that animations haven't settled, which results in tests hanging for long periods of time, showing the following message in the console:
Wait for <myAppIdentifier> to idle
From the docs on fractionComplete
:
Changing the value of this property on an inactive animator moves it to the active state.
There's a bit more info on this here that I found helpful in solving this code's behavior with UITests:
https://diggingdeveloper.blog/2022/01/21/xcode-ui-tests-infinite-wait-for-app-to-idle/
As a workaround, you could choose to disable this code with a custom environment variable like isUITesting
.
override func draw(_ rect: CGRect) {
super.draw(rect)
effect = nil
animator?.stopAnimation(true)
animator = UIViewPropertyAnimator(duration: 1, curve: .linear) { [unowned self] in
self.effect = theEffect
}
animator?.fractionComplete = customIntensity
DispatchQueue.main.async { [weak self] in
self?.animator.stopAnimation(true)
self?.animator.finishAnimation(at: .current)
}
}
for cells and view states, you can finish animation