用户头像的背景为头像的模糊头像时候

//模糊函数
UIImage *img = [UIImage
imageNamed:@"0"];//输入
CGFloat outputAspectRatio =
SCREEN_WITH/SCREEN_WITH;//输出宽高比
CIFilter *gaussianBlurFilter = [CIFilter
filterWithName:@"CIGaussianBlur"];
[gaussianBlurFilter setDefaults];
CIImage *inputImage = [CIImage
imageWithCGImage:[img CGImage]];
[gaussianBlurFilter setValue:inputImage
forKey:kCIInputImageKey];
[gaussianBlurFilter setValue:@5
forKey:kCIInputRadiusKey];//模糊半径

CIImage *outputImage = [gaussianBlurFilter
outputImage];
CIContext *context = [CIContext
contextWithOptions:nil];
CGSize imageSize = [outputImage
extent].size;
CGSize outputSize =
CGSizeMake(imageSize.width, imageSize.width/outputAspectRatio);
CGImageRef cgimg = [context
createCGImage:outputImage
fromRect:CGRectMake(0,
(imageSize.height - outputSize.height)/2,
outputSize.width,
outputSize.height)];
UIImage *image = [UIImage
imageWithCGImage:cgimg];//输出
CGImageRelease(cgimg);