IOS UIImage 模糊

#import <UIKit/UIKit.h>
#import <Accelerate/Accelerate.h>
#import <QuartzCore/QuartzCore.h>

@interface UIImage (Blur)

// 0.0 to 1.0
- (UIImage*)blurredImage:(CGFloat)blurAmount;

@end

#import "UIImage+Blur.h"

@implementation UIImage (Blur)

- (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;
}

@end

// 使用 

UIImage *image = [[UIImage imageNamed:@"xxxx.png"] blurredImage:0.6];