iOS图片模糊效果的实现方法

#import "ViewController.h" 
#import <Accelerate/Accelerate.h> 
 
@interface ViewController () 
 
@end 
 
@implementation ViewController 
 
- (void)viewDidLoad { 
 [super viewDidLoad]; 
 self.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"background"]]; 
  
// [self iOS8BlurImageImplement]; 
// [self coreImageImplement]; 
 [self vImageImplement]; 
} 
 
// iOS8 使用系统自带的处理方式 
- (void)iOS8BlurImageImplement { 
 UIBlurEffect *beffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight]; 
 UIVisualEffectView *view = [[UIVisualEffectView alloc] initWithEffect:beffect]; 
 view.frame = self.view.bounds; 
 [self.view addSubview:view]; 
} 
 
 
// 使用CoreImage实现图片模糊 
- (void)coreImageImplement{ 
 CIContext *context = [CIContext contextWithOptions:nil]; 
  
 NSError *error = nil; 
 NSString *filePath = [[NSBundle mainBundle] pathForResource:@"background" ofType:@"png"]; 
 NSData *imageData = [NSData dataWithContentsOfFile:filePath options:NSDataReadingUncached error:&error]; 
  
 //NSData *imageData = [NSData dataWithContentsOfFile:@"background.png"]; 
 CIImage *image = [CIImage imageWithData:imageData]; 
 CIFilter *filter = [CIFilter filterWithName:@"CIGaussianBlur"]; 
 [filter setValue:image forKey:kCIInputImageKey]; 
 [filter setValue:@2.0f forKey:@"inputRadius"]; 
 CIImage *result = [filter valueForKey:kCIOutputImageKey]; 
 CGImageRef outImage = [context createCGImage:result fromRect:[result extent]]; 
 UIImage *bluerImage = [UIImage imageWithCGImage:outImage]; 
  
 UIImageView *imageView = [[UIImageView alloc] initWithImage:bluerImage]; 
 imageView.frame = self.view.bounds; 
 [self.view addSubview:imageView]; 
} 
 
 
// 使用vImage API实现图片模糊 
// iOS5.0中新增了vImage API可以使用，它属于Accelerate.Framework，所以如果你要使用它要在工程中加入这个Framework。模糊算法使用的是vImageBoxConvolve_ARGB8888这个函数。 
- (void)vImageImplement { 
 UIImage *image = [UIImage imageNamed:@"background"]; 
 UIImage *blurImage = [self blurryImage:image withBlurLevel:0.5]; 
 self.view.backgroundColor = [UIColor colorWithPatternImage:blurImage]; 
} 
 
- (UIImage *)blurryImage:(UIImage *)image withBlurLevel:(CGFloat)blur { 
 if (blur < 0.f || blur > 1.f) { 
  blur = 0.5f; 
 } 
 int boxSize = (int)(blur * 100); 
 boxSize = boxSize - (boxSize % 2) + 1; 
  
 CGImageRef img = image.CGImage; 
  
 vImage_Buffer inBuffer, outBuffer; 
 vImage_Error error; 
  
 voidvoid *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(@"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); 
  
 CGColorSpaceRelease(colorSpace); 
 CGImageRelease(imageRef); 
  
 return returnImage; 
} 
 
@end