CODEWITHSUNDEEP
iosobjective-cuiblureffectuivisualeffectview
BBruce
BBruce

Reputation: 265

iOS 8 UIVisualEffect View with UIBlurEffect becomes opaque

I am trying to present a view with a blurred transparent background over an existing view. I am able to get the desired effect during the presentation animation, but once the blurred view is fully presented, it becomes opaque.

Here's how I am presenting it:

if (!UIAccessibilityIsReduceTransparencyEnabled()) {
    UIBlurEffect *blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight];
    UIVisualEffectView *blurEffectView = [[UIVisualEffectView alloc] initWithEffect:blurEffect];
    blurEffectView.frame = self.view.bounds;
    [blurEffectView setOpaque:NO];
    [self.view insertSubview:blurEffectView atIndex:0];
    [blurEffectView setTranslatesAutoresizingMaskIntoConstraints:false];
}

In my blurred view, I have set the background color to clear color and opaque to NO. Any thoughts?

Upvotes: 4

Views: 4837

Answers (4)

Nimrod Gruber
Nimrod Gruber

Reputation: 3

Simply set the view controller which holds the blurred view like this: myViewController.modalPresentationStyle = UIModalPresentationOverCurrentContext;

It prevents optimisation which removes views from the view hierarchy which in turn makes the blurred view presented first and thus making it opaque.

Upvotes: 0

Olivier
Olivier

Reputation: 901

Note that any UIVisualEffectView with a UIBlurEffect will be opaque if the "Reduce Transparency" accessibility setting is on.

(Settings > General > Accessibility > Increase Contrast > Reduce Transparency)

(Which is what your are actually checking with your if (!UIAccessibilityIsReduceTransparencyEnabled()) statement.)

Upvotes: 1

JonEasy
JonEasy

Reputation: 1013

From the documentation:

A UIBlurEffect object applies a blurring effect to the content layered behind a UIVisualEffectView.

So I think the problem is your clear backgroundColor. If you have some kind of content or coloring behind your UIVisualEffectView, it should work.

UIBlurEffect *blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleExtraLight];
UIVisualEffectView *blurredView = [[UIVisualEffectView alloc] initWithEffect:blurEffect];

This simple code snippet does work for me. In the ViewController I want to show the blurred effect I just call [[self view] addSubView:blurredView]

Upvotes: 0

BBruce
BBruce

Reputation: 265

I wound up writing a custom presentation controller. Never found a way to do this with standard presentations.

In the view where I want the effect viewDidLoad:

//Custom Modal Presentation
[self setModalPresentationStyle:UIModalPresentationCustom];

//blur the controlContainerView
if (!UIAccessibilityIsReduceTransparencyEnabled()) {

    UIBlurEffect *blurEffect = [UIBlurEffect effectWithStyle:[self blurStyle]];
    UIVisualEffectView *blurEffectView = [[UIVisualEffectView alloc] initWithEffect:blurEffect];
    blurEffectView.frame = self.controlContainerView.bounds;
    [blurEffectView setOpaque:NO];
    [self.controlContainerView insertSubview:blurEffectView atIndex:0];
    [blurEffectView setTranslatesAutoresizingMaskIntoConstraints:false];
}

Invoking the above view:

//in .h
@property (nonatomic) id<UIViewControllerTransitioningDelegate> transitioningDelegate;

//In .m
BlurViewController *blurVC = [self.storyboard instantiateViewControllerWithIdentifier:@"blurView"];
_transitioningDelegate = [[MyCustomOverlayDelegate alloc] init];
[blurView setModalPresentationStyle:UIModalPresentationCustom];
[blurView setTransitioningDelegate:[self transitioningDelegate]];
[blurView setBlurStyle:UIBlurEffectStyleLight];
[self presentViewController: blurView animated:YES completion:nil];

You will also need to import the entire stack of presentation controller classes. For me, these were OverlayDelegate, OverlayTransitionAnimator, and OverlayPresentationController. This is where the real work is.

If you can, check out WWDC 2014 session 228 "A look inside presentation controllers". Custom presentations are covered about half-way through. It was what I used to base my custom stack on and reasonably straight forward.

Upvotes: 0

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