How can I produce an effect similar to the iOS 7 blur view?

Question

I'm trying to replicate this blurred background from Apple's publicly released iOS 7 example screen:

This question suggests applying a CI filter to the contents below, but that's a whole different approach. It's obvious that iOS 7 doesn't capture the contents of the views below, for many reasons:

1. Doing some rough testing, capturing a screenshot of the views below and applying a CIGaussianBlur filter with a large enough radius to mimic iOS 7's blur style takes 1-2 seconds, even on a simulator.
2. The iOS 7 blur view is able to blur over dynamic views, such as a video or animations, with no noticeable lag.

Can anyone hypothesize what frameworks they could be using to create this effect, and if it's possible to create a similar effect with current public APIs?

Edit: (from comment) We don't exactly know how Apple is doing it, but are there any basic assumptions we can make? We can assume they are using hardware, right?

Is the effect self-contained in each view, such that the effect doesn't actually know what's behind it? Or must, based on how blurs work, the contents behind the blur be taken into consideration?

If the contents behind the effect are relevant, can we assume that Apple is receiving a "feed" of the contents below and continuously rendering them with a blur?

Atheling

(I think we can assume that apple is using pure GL to render the home screens anyway. I doubt they're abstracting it with UIViews and other things which would degrade performance, since it's such a key part of the OS) – Castellanos

As I indicated in the comments to my answer here: https://mcmap.net/q/128197/-ios-7-style-blur-view they wrote the OS, so of course they're going to have accelerated access to the contents of layers composited below the current view. We can see some of what they might be using in the private IOSurface API: #14135715 . Gaussian blurs can be made much faster than the generalized Gaussian blur cases if they have a fixed radius, or even use interesting optimizations like integral images. – Freud

@BradLarson - To paraphrase Jessica Simpson... I have no idea what all that means but it sounds cool as heck! But seriously, are you saying that you can use a partially transparent view with a a blur filter and lay it over another view to achieve this effect? – Dendy

https://mcmap.net/q/86518/-creating-a-blurring-overlay-view worked perfectly for me the first time i tried it, and was concise – Salome

Answer 1

Why bother replicating the effect? Just draw a UIToolbar behind your view.

myView.backgroundColor = [UIColor clearColor];
UIToolbar* bgToolbar = [[UIToolbar alloc] initWithFrame:myView.frame];
bgToolbar.barStyle = UIBarStyleDefault;
[myView.superview insertSubview:bgToolbar belowSubview:myView];

Inapprehensive

I disagree with crizzwald. I don't think that's a good interpretation of the rules of expectation of what APple will do. – Claudio

This is a great solution! Apple certainly won't reject you for making your app look great! – Symposiac

This just gives a translucency effect but does not blur the contents of view behind the toolbar. – Disfeature

It does work but as with system-wide blur effects it only works on newer devices. – Grinnell

This is not a future-proof method, since Apple can change the look of it in any major update. – Shizue

I ran this approach by an Apple UIKit engineer this week at their Tech Talks lab. While he certainly would not endorse this approach, he recognized the need for the effect and the lack of real public API for this, and said that this approach was the "least evil" option for now and is fairly safe as written. Specifically he said do not try to do any animations of the frame or transform of this toolbar/view or anything like that, or bad things will happen. He also strongly suggested to file Radar bug reports on this, to build a case internally so we can get a real public API for this effect! – Hyperthermia

Interesting...it looks like the account @Inapprehensive was created just to answer this question anonymously. Makes you wonder if this is not an unofficial post by someone who knows more than the rest of us about these things :) – Hyperthermia

This does not work on iPhone 4 running iOS 7. It is probably because on iPhone 4, since the GPU power is too low, the system does not add the usual blur effect to it's UITabBar itself. – Supranational

How do I make it non-white? If I change the background color for toolbar, it does not show the blur. – Badminton

@NikitaP Use the black bar style. – Credent

Now that iOS 8 has provided an API for this, here's a bit of code to target both iOS 7 and 8: https://mcmap.net/q/128199/-frosted-glass-ios-7-blur-effect – Haupt

Answer 2

Apple released code at WWDC as a category on UIImage that includes this functionality, if you have a developer account you can grab the UIImage category (and the rest of the sample code) by going to this link: https://developer.apple.com/wwdc/schedule/ and browsing for section 226 and clicking on details. I haven't played around with it yet but I think the effect will be a lot slower on iOS 6, there are some enhancements to iOS 7 that make grabbing the initial screen shot that is used as input to the blur a lot faster.

Direct link: https://developer.apple.com/downloads/download.action?path=wwdc_2013/wwdc_2013_sample_code/ios_uiimageeffects.zip

Muddleheaded

I see the video, I can watch it, but can't figure out where to download the sample code! – Proverbial

I didn't see much difference compared to a simple background alpha change; perhaps it's because I'm displaying videos and they just need more blur ... – Ginter

Answer 3

Actually I'd bet this would be rather simple to achieve. It probably wouldn't operate or look exactly like what Apple has going on but could be very close.

First of all, you'd need to determine the CGRect of the UIView that you will be presenting. Once you've determine that you would just need to grab an image of the part of the UI so that it can be blurred. Something like this...

- (UIImage*)getBlurredImage {
    // You will want to calculate this in code based on the view you will be presenting.
    CGSize size = CGSizeMake(200,200);

    UIGraphicsBeginImageContext(size);
    [view drawViewHierarchyInRect:(CGRect){CGPointZero, w, h} afterScreenUpdates:YES]; // view is the view you are grabbing the screen shot of. The view that is to be blurred.
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    // Gaussian Blur
    image = [image applyLightEffect];

    // Box Blur
    // image = [image boxblurImageWithBlur:0.2f];

    return image;
}

Gaussian Blur - Recommended

Using the UIImage+ImageEffects Category Apple's provided here, you'll get a gaussian blur that looks very much like the blur in iOS 7.

Box Blur

You could also use a box blur using the following boxBlurImageWithBlur: UIImage category. This is based on an algorythem that you can find here.

@implementation UIImage (Blur)

-(UIImage *)boxblurImageWithBlur:(CGFloat)blur {
    if (blur < 0.f || blur > 1.f) {
        blur = 0.5f;
    }
    int boxSize = (int)(blur * 50);
    boxSize = boxSize - (boxSize % 2) + 1;

    CGImageRef img = self.CGImage;

    vImage_Buffer inBuffer, outBuffer;

    vImage_Error error;

    void *pixelBuffer;

    CGDataProviderRef inProvider = CGImageGetDataProvider(img);
    CFDataRef inBitmapData = CGDataProviderCopyData(inProvider);

    inBuffer.width = CGImageGetWidth(img);
    inBuffer.height = CGImageGetHeight(img);
    inBuffer.rowBytes = CGImageGetBytesPerRow(img);

    inBuffer.data = (void*)CFDataGetBytePtr(inBitmapData);

    pixelBuffer = malloc(CGImageGetBytesPerRow(img) * CGImageGetHeight(img));

    if(pixelBuffer == NULL)
        NSLog(@"No pixelbuffer");

    outBuffer.data = pixelBuffer;
    outBuffer.width = CGImageGetWidth(img);
    outBuffer.height = CGImageGetHeight(img);
    outBuffer.rowBytes = CGImageGetBytesPerRow(img);

    error = vImageBoxConvolve_ARGB8888(&inBuffer, &outBuffer, NULL, 0, 0, boxSize, boxSize, NULL, kvImageEdgeExtend);

    if (error) {
        NSLog(@"JFDepthView: error from convolution %ld", error);
    }

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGContextRef ctx = CGBitmapContextCreate(outBuffer.data,
                                         outBuffer.width,
                                         outBuffer.height,
                                         8,
                                         outBuffer.rowBytes,
                                         colorSpace,
                                         kCGImageAlphaNoneSkipLast);
    CGImageRef imageRef = CGBitmapContextCreateImage (ctx);
    UIImage *returnImage = [UIImage imageWithCGImage:imageRef];

    //clean up
    CGContextRelease(ctx);
    CGColorSpaceRelease(colorSpace);

    free(pixelBuffer);
    CFRelease(inBitmapData);

    CGImageRelease(imageRef);

    return returnImage;
}

@end

Now that you are calculating the screen area to blur, passing it into the blur category and receiving a UIImage back that has been blurred, now all that is left is to set that blurred image as the background of the view you will be presenting. Like I said, this will not be a perfect match for what Apple is doing, but it should still look pretty cool.

Hope it helps.

Allman

It seems that the blurred image's blue color and red color are swopped. – Unequaled

It looks like someone has used your code to create this project: github.com/alexdrone/ios-realtimeblur/blob/master/RealTimeBlur/… but unfortunately there is no attribution, and they've added an "All Rights Reserved" copyright statement at the top. – Chiu

@Mark, thanks for the heads up. However, this blurring algorithm is not my own. I already mentioned where I got it from in my post above. As it says in my post "This is based on an algorythem that you can find here." with a link to indieambitions.com/idevblogaday/… I will definitely send this person a message and let them know they are missing attribution. Thanks – Allman

@MarkErdmann take a look at your own files in xcode. It has "All Rights Reserved". Its a generic thing that xcode adds. Also the author added just added a license.md which says its lisenced under the mit lisence – Vaillancourt

Don't use renderInContext, use the new drawViewHierarchyInRect: or snapshotView:. WWDC talk 216 "Implementing Engaging UI on iOS7" claims a 5-15x performance improvement. – Vise

@Vise Thanks, I've edited the answer and added drawViewHierarchyInRect:afterScreenUpdates: – Allman

Answer 4

iOS8 answered these questions.

- (instancetype)initWithEffect:(UIVisualEffect *)effect

or Swift:

init(effect effect: UIVisualEffect)

Measures

I guess this solution is mostly useless until iOS 9 is out. The majority of applications still support iOS 7, and this solution is not supported there. – Meaghan

true true, you can use this kind of thing for now: github.com/nicklockwood/FXBlurView – Measures

I implemented this with the Xcode 6 toolchain with iOS8, and it works great. I tried to implement using the CPU, but works noticeably slower than this method. – Stammel

Why to code when Xcode provides in storyboard itself!!!!! Thanks @AdamWaite – Gavrilla

Answer 5

I just wrote my little subclass of UIView that has ability to produce native iOS 7 blur on any custom view. It uses UIToolbar but in a safe way for changing it's frame, bounds, color and alpha with real-time animation.

Please let me know if you notice any problems.

https://github.com/ivoleko/ILTranslucentView

Potheen

I have tried some other approaches (like adding a UIToolbar myself, or Apple's UIImage+ImageEffects.h category); your was the best and easiest solution. Thanks! – Waterworks

How well does it react to the new iOS 7.0.3 download? Other classes that have used this technique don't render correctly anymore :[ – Necrophilism

@achi, I did not notice any problem with iOS 7.0.3. – Potheen

Do you know if any apps that animate using your approach and have been accepted by Apple? – Abbotsen

Hi guys. Yes, app that use this class will be approved by Apple! – Potheen

Answer 6

There is a rumor that Apple engineers claimed, to make this performant they are reading directly out of the gpu buffer which raises security issues which is why there is no public API to do this yet.

Atrocity

If this is true then that is - by far - the worst solution ever. – Casseycassi

aaaaaand the blur is removed from iOS 7. – Alien

It was only removed on devices that were seeing performance issues. – Atrocity

Is this post the source of the rumor? :) – Unfair

That rumor is probably bunk. OpenGL ES 2.0 on iOS allows you to read and write to framebuffers without any security risk. The blur is done using GLSL shaders, which is why it runs fast. – Symposiac

Answer 7

Here is a really easy way of doing it:https://github.com/JagCesar/iOS-blur

Just copy the layer of UIToolbar and you're done, AMBlurView does it for you. Okay, it's not as blurry as control center, but is's blurry enough.

Remember that iOS7 is under NDA.

Satori

Answer 8

You can find your solution from apple's DEMO in this page: WWDC 2013 , find out and download UIImageEffects sample code.

Then with @Jeremy Fox's code. I changed it to

- (UIImage*)getDarkBlurredImageWithTargetView:(UIView *)targetView
{
    CGSize size = targetView.frame.size;

    UIGraphicsBeginImageContext(size);
    CGContextRef c = UIGraphicsGetCurrentContext();
    CGContextTranslateCTM(c, 0, 0);
    [targetView.layer renderInContext:c]; // view is the view you are grabbing the screen shot of. The view that is to be blurred.
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return [image applyDarkEffect];
}

Hope this will help you.

Rowel

Answer 9

This is a solution that you can see in the vidios of the WWDC. You have to do a Gaussian Blur, so the first thing you have to do is to add a new .m and .h file with the code i'm writing here, then you have to make and screen shoot, use the desired effect and add it to your view, then your UITable UIView or what ever has to be transparent, you can play with applyBlurWithRadius, to archive the desired effect, this call works with any UIImage.

At the end the blured image will be the background and the rest of the controls above has to be transparent.

For this to work you have to add the next libraries:

Acelerate.framework,UIKit.framework,CoreGraphics.framework

I hope you like it.

Happy coding.

    //Screen capture.
    UIGraphicsBeginImageContext(self.view.bounds.size);

    CGContextRef c = UIGraphicsGetCurrentContext();
    CGContextTranslateCTM(c, 0, 0);
    [self.view.layer renderInContext:c];

    UIImage* viewImage = UIGraphicsGetImageFromCurrentImageContext();
    viewImage = [viewImage applyLightEffect];

    UIGraphicsEndImageContext();

    //.h FILE
    #import <UIKit/UIKit.h>

    @interface UIImage (ImageEffects)

   - (UIImage *)applyLightEffect;
   - (UIImage *)applyExtraLightEffect;
   - (UIImage *)applyDarkEffect;
   - (UIImage *)applyTintEffectWithColor:(UIColor *)tintColor;

   - (UIImage *)applyBlurWithRadius:(CGFloat)blurRadius tintColor:(UIColor *)tintColor saturationDeltaFactor:(CGFloat)saturationDeltaFactor maskImage:(UIImage *)maskImage;

   @end

    //.m FILE
    #import "cGaussianEffect.h"
    #import <Accelerate/Accelerate.h>
    #import <float.h>


     @implementation UIImage (ImageEffects)


    - (UIImage *)applyLightEffect
    {
        UIColor *tintColor = [UIColor colorWithWhite:1.0 alpha:0.3];
        return [self applyBlurWithRadius:1 tintColor:tintColor saturationDeltaFactor:1.8 maskImage:nil];
    }


    - (UIImage *)applyExtraLightEffect
    {
        UIColor *tintColor = [UIColor colorWithWhite:0.97 alpha:0.82];
        return [self applyBlurWithRadius:1 tintColor:tintColor saturationDeltaFactor:1.8 maskImage:nil];
    }


    - (UIImage *)applyDarkEffect
    {
        UIColor *tintColor = [UIColor colorWithWhite:0.11 alpha:0.73];
        return [self applyBlurWithRadius:1 tintColor:tintColor saturationDeltaFactor:1.8 maskImage:nil];
    }


    - (UIImage *)applyTintEffectWithColor:(UIColor *)tintColor
    {
        const CGFloat EffectColorAlpha = 0.6;
        UIColor *effectColor = tintColor;
        int componentCount = CGColorGetNumberOfComponents(tintColor.CGColor);
        if (componentCount == 2) {
            CGFloat b;
            if ([tintColor getWhite:&b alpha:NULL]) {
                effectColor = [UIColor colorWithWhite:b alpha:EffectColorAlpha];
            }
        }
        else {
            CGFloat r, g, b;
            if ([tintColor getRed:&r green:&g blue:&b alpha:NULL]) {
                effectColor = [UIColor colorWithRed:r green:g blue:b alpha:EffectColorAlpha];
            }
        }
        return [self applyBlurWithRadius:10 tintColor:effectColor saturationDeltaFactor:-1.0 maskImage:nil];
    }


    - (UIImage *)applyBlurWithRadius:(CGFloat)blurRadius tintColor:(UIColor *)tintColor saturationDeltaFactor:(CGFloat)saturationDeltaFactor maskImage:(UIImage *)maskImage
    {
        if (self.size.width < 1 || self.size.height < 1) {
            NSLog (@"*** error: invalid size: (%.2f x %.2f). Both dimensions must be >= 1: %@", self.size.width, self.size.height, self);
            return nil;
        }
        if (!self.CGImage) {
            NSLog (@"*** error: image must be backed by a CGImage: %@", self);
            return nil;
        }
        if (maskImage && !maskImage.CGImage) {
            NSLog (@"*** error: maskImage must be backed by a CGImage: %@", maskImage);
            return nil;
        }

        CGRect imageRect = { CGPointZero, self.size };
        UIImage *effectImage = self;

        BOOL hasBlur = blurRadius > __FLT_EPSILON__;
        BOOL hasSaturationChange = fabs(saturationDeltaFactor - 1.) > __FLT_EPSILON__;
        if (hasBlur || hasSaturationChange) {
            UIGraphicsBeginImageContextWithOptions(self.size, NO, [[UIScreen mainScreen] scale]);
            CGContextRef effectInContext = UIGraphicsGetCurrentContext();
            CGContextScaleCTM(effectInContext, 1.0, -1.0);
            CGContextTranslateCTM(effectInContext, 0, -self.size.height);
            CGContextDrawImage(effectInContext, imageRect, self.CGImage);

            vImage_Buffer effectInBuffer;
            effectInBuffer.data     = CGBitmapContextGetData(effectInContext);
            effectInBuffer.width    = CGBitmapContextGetWidth(effectInContext);
            effectInBuffer.height   = CGBitmapContextGetHeight(effectInContext);
            effectInBuffer.rowBytes = CGBitmapContextGetBytesPerRow(effectInContext);

            UIGraphicsBeginImageContextWithOptions(self.size, NO, [[UIScreen mainScreen] scale]);
            CGContextRef effectOutContext = UIGraphicsGetCurrentContext();
            vImage_Buffer effectOutBuffer;
            effectOutBuffer.data     = CGBitmapContextGetData(effectOutContext);
            effectOutBuffer.width    = CGBitmapContextGetWidth(effectOutContext);
            effectOutBuffer.height   = CGBitmapContextGetHeight(effectOutContext);
            effectOutBuffer.rowBytes = CGBitmapContextGetBytesPerRow(effectOutContext);

            if (hasBlur) {
                CGFloat inputRadius = blurRadius * [[UIScreen mainScreen] scale];
                NSUInteger radius = floor(inputRadius * 3. * sqrt(2 * M_PI) / 4 + 0.5);
                if (radius % 2 != 1) {
                    radius += 1;
                }
                vImageBoxConvolve_ARGB8888(&effectInBuffer, &effectOutBuffer, NULL, 0, 0, radius, radius, 0, kvImageEdgeExtend);
                vImageBoxConvolve_ARGB8888(&effectOutBuffer, &effectInBuffer, NULL, 0, 0, radius, radius, 0, kvImageEdgeExtend);
                vImageBoxConvolve_ARGB8888(&effectInBuffer, &effectOutBuffer, NULL, 0, 0, radius, radius, 0, kvImageEdgeExtend);
            }
            BOOL effectImageBuffersAreSwapped = NO;
            if (hasSaturationChange) {
                CGFloat s = saturationDeltaFactor;
                CGFloat floatingPointSaturationMatrix[] = {
                    0.0722 + 0.9278 * s,  0.0722 - 0.0722 * s,  0.0722 - 0.0722 * s,  0,
                    0.7152 - 0.7152 * s,  0.7152 + 0.2848 * s,  0.7152 - 0.7152 * s,  0,
                    0.2126 - 0.2126 * s,  0.2126 - 0.2126 * s,  0.2126 + 0.7873 * s,  0,
                                  0,                    0,                    0,  1,
                };
                const int32_t divisor = 256;
                NSUInteger matrixSize = sizeof(floatingPointSaturationMatrix)/sizeof(floatingPointSaturationMatrix[0]);
                int16_t saturationMatrix[matrixSize];
                for (NSUInteger i = 0; i < matrixSize; ++i) {
                    saturationMatrix[i] = (int16_t)roundf(floatingPointSaturationMatrix[i] * divisor);
                }
                if (hasBlur) {
                    vImageMatrixMultiply_ARGB8888(&effectOutBuffer, &effectInBuffer, saturationMatrix, divisor, NULL, NULL, kvImageNoFlags);
                    effectImageBuffersAreSwapped = YES;
                }
                else {
                    vImageMatrixMultiply_ARGB8888(&effectInBuffer, &effectOutBuffer, saturationMatrix, divisor, NULL, NULL, kvImageNoFlags);
                }
            }
            if (!effectImageBuffersAreSwapped)
                effectImage = UIGraphicsGetImageFromCurrentImageContext();
            UIGraphicsEndImageContext();

            if (effectImageBuffersAreSwapped)
                effectImage = UIGraphicsGetImageFromCurrentImageContext();
            UIGraphicsEndImageContext();
        }

        UIGraphicsBeginImageContextWithOptions(self.size, NO, [[UIScreen mainScreen] scale]);
        CGContextRef outputContext = UIGraphicsGetCurrentContext();
        CGContextScaleCTM(outputContext, 1.0, -1.0);
        CGContextTranslateCTM(outputContext, 0, -self.size.height);

        CGContextDrawImage(outputContext, imageRect, self.CGImage);

        if (hasBlur) {
            CGContextSaveGState(outputContext);
            if (maskImage) {
                CGContextClipToMask(outputContext, imageRect, maskImage.CGImage);
            }
            CGContextDrawImage(outputContext, imageRect, effectImage.CGImage);
            CGContextRestoreGState(outputContext);
        }

        if (tintColor) {
            CGContextSaveGState(outputContext);
            CGContextSetFillColorWithColor(outputContext, tintColor.CGColor);
            CGContextFillRect(outputContext, imageRect);
            CGContextRestoreGState(outputContext);
        }

        UIImage *outputImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();

        return outputImage;
    }

Blasphemous

Answer 10

Every response here is using vImageBoxConvolve_ARGB8888 this function is really, really slow, that is fine, if the performance is not a high priority requirement, but if you are using this for transitioning between two View Controllers (for example) this approach means times over 1 second or maybe more, that is very bad to the user experience of your application.

If you prefer leave all this image processing to the GPU (And you should) you can get a much better effect and also awesome times rounding 50ms (supposing that you have a time of 1 second in the first approach), so, lets do it.

First download the GPUImage Framework (BSD Licensed) here.

Next, Add the following classes (.m and .h) from the GPUImage (I'm not sure that these are the minimum needed for the blur effect only)

• GPUImage.h
• GPUImageAlphaBlendFilter
• GPUImageFilter
• GPUImageFilterGroup
• GPUImageGaussianBlurPositionFilter
• GPUImageGaussianSelectiveBlurFilter
• GPUImageLuminanceRangeFilter
• GPUImageOutput
• GPUImageTwoInputFilter
• GLProgram
• GPUImageBoxBlurFilter
• GPUImageGaussianBlurFilter
• GPUImageiOSBlurFilter
• GPUImageSaturationFilter
• GPUImageSolidColorGenerator
• GPUImageTwoPassFilter

• GPUImageTwoPassTextureSamplingFilter

• iOS/GPUImage-Prefix.pch

• iOS/GPUImageContext
• iOS/GPUImageMovieWriter
• iOS/GPUImagePicture
• iOS/GPUImageView

Next, create a category on UIImage, that will add a blur effect to an existing UIImage:

#import "UIImage+Utils.h"

#import "GPUImagePicture.h"
#import "GPUImageSolidColorGenerator.h"
#import "GPUImageAlphaBlendFilter.h"
#import "GPUImageBoxBlurFilter.h"

@implementation UIImage (Utils)

- (UIImage*) GPUBlurredImage
{
    GPUImagePicture *source =[[GPUImagePicture alloc] initWithImage:self];

    CGSize size = CGSizeMake(self.size.width * self.scale, self.size.height * self.scale);

    GPUImageBoxBlurFilter *blur = [[GPUImageBoxBlurFilter alloc] init];
    [blur setBlurRadiusInPixels:4.0f];
    [blur setBlurPasses:2.0f];
    [blur forceProcessingAtSize:size];
    [source addTarget:blur];

    GPUImageSolidColorGenerator * white = [[GPUImageSolidColorGenerator alloc] init];

    [white setColorRed:1.0f green:1.0f blue:1.0f alpha:0.1f];
    [white forceProcessingAtSize:size];

    GPUImageAlphaBlendFilter * blend = [[GPUImageAlphaBlendFilter alloc] init];
    blend.mix = 0.9f;

    [blur addTarget:blend];
    [white addTarget:blend];

    [blend forceProcessingAtSize:size];
    [source processImage];

    return [blend imageFromCurrentlyProcessedOutput];
}

@end

And last, add the following frameworks to your project:

AVFoundation CoreMedia CoreVideo OpenGLES

Yeah, got fun with this much faster approach ;)

Aedile

Answer 11

You can try using my custom view, which has capability to blur the background. It does this by faking taking snapshot of the background and blur it, just like the one in Apple's WWDC code. It is very simple to use.

I also made some improvement over to fake the dynamic blur without losing the performance. The background of my view is a scrollView which scrolls with the view, thus provide the blur effect for the rest of the superview.

See the example and code on my GitHub

Jermainejerman

Answer 12

Core Background implements the desired iOS 7 effect.

https://github.com/justinmfischer/core-background

Disclaimer: I am the author of this project

Aegospotami