加入  CoreImage.framework  CoreGraphic.framework 等库
在使用时引入：#import<Accelerate/Accelerate.h> ，支持iOS 5.0 及以上。
-(void)show
{
    UIImage* img = [self getBlurImage:[UIImage imageNamed:@"Default-568h.png"]];
    [_bgImageView setImage:img];
}
-(UIImage*)getBlurImage:(UIImage*)image
{
    return [self gaussBlur:0.2 andImage:image];
}
- (UIImage*)gaussBlur:(CGFloat)blurLevel andImage:(UIImage*)originImage
{
    blurLevel = MIN(1.0,MAX(0.0, blurLevel));
    //int boxSize = (int)(blurLevel * 0.1 * MIN(self.size.width, self.size.height));
    int boxSize = 50;//模糊度。
    boxSize = boxSize - (boxSize % 2) + 1;
    NSData *imageData = UIImageJPEGRepresentation(originImage, 1);
    UIImage *tmpImage = [UIImage imageWithData:imageData];
    CGImageRef img = tmpImage.CGImage;
    vImage_Buffer inBuffer, outBuffer;
    vImage_Error error;
    void *pixelBuffer;
    //create vImage_Buffer with data from CGImageRef
    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);
    //create vImage_Buffer for output
    pixelBuffer = malloc(CGImageGetBytesPerRow(img) *CGImageGetHeight(img));
    outBuffer.data = pixelBuffer;
    outBuffer.width = CGImageGetWidth(img);
    outBuffer.height = CGImageGetHeight(img);
    outBuffer.rowBytes = CGImageGetBytesPerRow(img);
    NSInteger windowR = boxSize/2;
    CGFloat sig2 = windowR / 3.0;
    if(windowR>0){ sig2 = -1/(2*sig2*sig2); }
    int16_t *kernel = (int16_t*)malloc(boxSize*sizeof(int16_t));
    int32_t  sum = 0;
    for(NSInteger i=0; i<boxSize; ++i){
        kernel[i] = 255*exp(sig2*(i-windowR)*(i-windowR));
        sum += kernel[i];
    }
    free(kernel);
    // convolution
    error = vImageConvolve_ARGB8888(&inBuffer, &outBuffer,NULL, 0, 0, kernel, boxSize, 1, sum, NULL, kvImageEdgeExtend);
    error = vImageConvolve_ARGB8888(&outBuffer, &inBuffer,NULL, 0, 0, kernel, 1, boxSize, sum, NULL, kvImageEdgeExtend);
    outBuffer = inBuffer;
    if (error) {
        //NSLog(@"error from convolution %ld", error);
    }
    CGColorSpaceRef colorSpace =CGColorSpaceCreateDeviceRGB();
    CGContextRef ctx = CGBitmapContextCreate(outBuffer.data,
                                             outBuffer.width,
                                             outBuffer.height,
                                             8,
                                             outBuffer.rowBytes,
                                             colorSpace,
                                             kCGBitmapAlphaInfoMask &kCGImageAlphaNoneSkipLast);
    CGImageRef imageRef =CGBitmapContextCreateImage(ctx);
    UIImage *returnImage = [UIImage imageWithCGImage:imageRef];
    //clean up
    CGContextRelease(ctx);
    CGColorSpaceRelease(colorSpace);
    free(pixelBuffer);
    CFRelease(inBitmapData);
    CGImageRelease(imageRef);
    return returnImage;
}