Swift version: 5.1
As of iOS 8.0, visual effects such as blur and vibrancy are a cinch because Apple provides a built in
UIView subclass that does all the hard work:
UIVisualEffectView. For example, if you want to blur an image, you would use this code:
let imageView = UIImageView(image: UIImage(named: "example")) imageView.frame = view.bounds imageView.contentMode = .scaleToFill view.addSubview(imageView) let blurEffect = UIBlurEffect(style: .dark) let blurredEffectView = UIVisualEffectView(effect: blurEffect) blurredEffectView.frame = imageView.bounds view.addSubview(blurredEffectView)
As well as blurring content, Apple also lets you add a "vibrancy" effect to your views – this is a translucency effect designed to ensure that text is readable when it's over any kind of blurred background, and it's used to create that soft glow effect you see in the notification center.
We could extend the previous example so that it adds a segmented control in the middle of the view, using a vibrancy effect. This is accomplished by created a second
UIVisualEffectView inside the first one, this time using
UIVibrancyEffect to create the glow. Note that you need to use the same blur type for both your visual effect views, otherwise the glow effect will be incorrect.
let segmentedControl = UISegmentedControl(items: ["First Item", "Second Item"]) segmentedControl.sizeToFit() segmentedControl.center = view.center let vibrancyEffect = UIVibrancyEffect(blurEffect: blurEffect) let vibrancyEffectView = UIVisualEffectView(effect: vibrancyEffect) vibrancyEffectView.frame = imageView.bounds vibrancyEffectView.contentView.addSubview(segmentedControl) blurredEffectView.contentView.addSubview(vibrancyEffectView)
Warning: you need to add child views to the
contentView property of a
UIVisualEffectView otherwise they will not be drawn correctly.
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Available from iOS 8.0
This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.
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