IOS中使得图片模糊的效果的方法

-(void)blurUserView

{

    

//     DOWN_IMAGE(userView, STRING_VALUE(userDict[@"avatar_big"]), SMALL_IMAGE);

    CIContext *context = [CIContext contextWithOptions:nil];

    CIImage *inputImage = [[CIImage alloc]initWithContentsOfURL:[NSURL URLWithString:STRING_VALUE(userDict[@"avatar_big"])]];

    CIFilter *filter = [CIFilter filterWithName:@"CIGaussianBlur"];

    [filter setValue:inputImage forKey:kCIInputImageKey];

    [filter setValue:[NSNumber numberWithFloat:2] forKey:@"inputRadius"];

    CIImage *result = [filter valueForKey:kCIOutputImageKey];

    

    CGImageRef cgImage = [context createCGImage:result fromRect:CGRectMake(0, -25, 180, 250)];

    UIImage *image = [UIImage imageWithCGImage:cgImage];

    CGImageRelease(cgImage);

    userView.image = image;

    

}