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