image helper from https://github.com/NZN/UIImage-Helpers

gistfile1.m

- (UIImage*)blurredImage:(CGFloat)blurAmount
{
    if (blurAmount < 0.0 || blurAmount > 1.0) {
        blurAmount = 0.5;
    }
    
    int boxSize = (int)(blurAmount * 40);
    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));
    
    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) {
        error = vImageBoxConvolve_ARGB8888(&outBuffer, &inBuffer, NULL, 0, 0, boxSize, boxSize, NULL, kvImageEdgeExtend);

        if (!error) {
            error = vImageBoxConvolve_ARGB8888(&inBuffer, &outBuffer, NULL, 0, 0, boxSize, boxSize, NULL, kvImageEdgeExtend);
        }
    }
    
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    
    CGContextRef ctx = CGBitmapContextCreate(outBuffer.data,
                                             outBuffer.width,
                                             outBuffer.height,
                                             8,
                                             outBuffer.rowBytes,
                                             colorSpace,
                                             (CGBitmapInfo)kCGImageAlphaNoneSkipLast);
    
    CGImageRef imageRef = CGBitmapContextCreateImage (ctx);
    
    UIImage *returnImage = [UIImage imageWithCGImage:imageRef];
    
    CGContextRelease(ctx);
    CGColorSpaceRelease(colorSpace);
    
    free(pixelBuffer);
    CFRelease(inBitmapData);
    
    CGColorSpaceRelease(colorSpace);
    CGImageRelease(imageRef);
    
    return returnImage;
}

+ (UIImage *)imageWithColor:(UIColor *)color
{
    CGRect rect = CGRectMake(0, 0, 1, 1);
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    CGContextSetFillColorWithColor(context, [color CGColor]);
    CGContextFillRect(context, rect);
    
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return image;
}

+ (UIImage *)screenshot
{
    CGSize imageSize = [[UIScreen mainScreen] bounds].size;
 
    if (NULL != UIGraphicsBeginImageContextWithOptions) {
        UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0);
    } else {
        UIGraphicsBeginImageContext(imageSize);
    }
    
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    for (UIWindow *window in [[UIApplication sharedApplication] windows]) {
        if (![window respondsToSelector:@selector(screen)] || [window screen] == [UIScreen mainScreen]) {
            CGContextSaveGState(context);

            CGContextTranslateCTM(context, [window center].x, [window center].y);

            CGContextConcatCTM(context, [window transform]);
            
            CGContextTranslateCTM(context,
                                  -[window bounds].size.width * [[window layer] anchorPoint].x,
                                  -[window bounds].size.height * [[window layer] anchorPoint].y);
            
            [[window layer] renderInContext:context];
            
            CGContextRestoreGState(context);
        }
    }
    
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    
    UIGraphicsEndImageContext();
    
    return image;
}