Creating a Blurring Overlay View

Creating a blurring overlay view

You can use UIVisualEffectView to achieve this effect. This is a native API that has been fine-tuned for performance and great battery life, plus it's easy to implement.


//only apply the blur if the user hasn't disabled transparency effects
if !UIAccessibility.isReduceTransparencyEnabled {
view.backgroundColor = .clear

let blurEffect = UIBlurEffect(style: .dark)
let blurEffectView = UIVisualEffectView(effect: blurEffect)
//always fill the view
blurEffectView.frame = self.view.bounds
blurEffectView.autoresizingMask = [.flexibleWidth, .flexibleHeight]

view.addSubview(blurEffectView) //if you have more UIViews, use an insertSubview API to place it where needed
} else {
view.backgroundColor = .black


//only apply the blur if the user hasn't disabled transparency effects
if (!UIAccessibilityIsReduceTransparencyEnabled()) {
self.view.backgroundColor = [UIColor clearColor];

UIBlurEffect *blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleDark];
UIVisualEffectView *blurEffectView = [[UIVisualEffectView alloc] initWithEffect:blurEffect];
//always fill the view
blurEffectView.frame = self.view.bounds;
blurEffectView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;

[self.view addSubview:blurEffectView]; //if you have more UIViews, use an insertSubview API to place it where needed
} else {
self.view.backgroundColor = [UIColor blackColor];

If you are presenting this view controller modally to blur the underlying content, you'll need to set the modal presentation style to Over Current Context and set the background color to clear to ensure the underlying view controller will remain visible once this is presented overtop.

Blurred overlay does not cover entire screen

First off, what Muhammad suggested should work. The reason your code crashes could be you are attempting to add the constraints first before adding the blurView to your view as a subview. The key phrase is:

they have no common ancestor.

Don't do that. Always add your subview before constraining it.

Lastly, one easy way to achieve what you want to achieve is to just toggle your navigationBar's visibility whenever you present your transparent screen (the one with the keyboard) and then put the navigationBar back to visible when you're done. Like so:

func overlayBlurredBackgroundView() {
self.navigationController?.navigationBar.isHidden = true

let blurredBackgroundView = UIVisualEffectView()
//blurredBackgroundView.frame = view.bounds
blurredBackgroundView.effect = UIBlurEffect(style: .systemThinMaterialDark)

blurredBackgroundView.translatesAutoresizingMaskIntoConstraints = false
blurredBackgroundView.topAnchor.constraint(equalTo: self.view.topAnchor, constant: 0.0).isActive = true
blurredBackgroundView.bottomAnchor.constraint(equalTo: self.view.bottomAnchor, constant: 0.0).isActive = true
blurredBackgroundView.leftAnchor.constraint(equalTo: self.view.leftAnchor, constant: 0.0).isActive = true
blurredBackgroundView.rightAnchor.constraint(equalTo: self.view.rightAnchor, constant: 0.0).isActive = true


and then putting it back when you're removing it:

func removeBlurredBackgroundView() {
self.navigationController?.navigationBar.isHidden = false
for subview in view.subviews {
if subview.isKind(of: UIVisualEffectView.self) {

Creating a blurView with a clear cut out

You can do it like this

    let scanLayer = CAShapeLayer()

let scanRect = CGRect.init(x: 100, y: 100, width: 200, height: 100)

let outerPath = UIBezierPath(rect: scanRect)

let superlayerPath = UIBezierPath.init(rect: blurView.frame)
outerPath.usesEvenOddFillRule = true
scanLayer.path = outerPath.cgPath
scanLayer.fillRule = kCAFillRuleEvenOdd
scanLayer.fillColor =

blurView.layer.mask = scanLayer

How to set the blur level of a view background

Android doesn't provide this functionality for UI elements as iOS does. It's not part of the UI rendering engine and to obtain these kind of effects you need to use third-party libraries which will essentially take a snapshot of the drawing cache, reduce its size for a faster processing and then put the generated bitmap into a view.

Here are some example libraries:

  • BlurrView
  • Blurry

Please bear in mind that this will have a serious performance hit on mid-low end phones.

How create transparent view with with blur effect?

I found an excellent tutorial that might help you to create a smooth transparent view with blur effect:

How to make Background ViewControllers should be blur when open SWRevealViewController from any ViewController

Thanks Finally i got the solution .

In Home view controller make these changes.

self.revealViewController.delegate = self;
- (void)revealController:(SWRevealViewController *)revealController didMoveToPosition:(FrontViewPosition)position
if (position == FrontViewPositionRight)
revealController.frontViewController.view.alpha = 0.5;
revealController.frontViewController.view.alpha = 1;

iOS Blur effect for a view behind when showing a UIView on top (dialog)

You can do this through many ways depending the iOS you are supporting. Here are two ways backwards compatible with before iOS8:

  • FXBlurView

  • iOS-Blur (Similar to you implement a UIToolbar view)

In iOS8 you can use a UIVisualEffectView. The process is simple and you can checkout this tutorial of Ray Wenderlich on how to do it.

Since you have asked a "programatically" way, here is a example using iOS-Blur library mentioned before:

JCRBlurView *blurView = [JCRBlurView new];
[blurView setFrame:CGRectMake(0.0f,0.0f,100.0f,100.0f)];
[self.view addSubview:blurView];

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