iOS实现图片高斯模糊效果

    CIContext *context = [CIContext contextWithOptions:nil];  
    CIImage *inputImage = [[CIImage alloc] initWithImage:[UIImage imageNamed:@"1.png"]];  
    // create gaussian blur filter  
    CIFilter *filter = [CIFilter filterWithName:@"CIGaussianBlur"];  
    [filter setValue:inputImage forKey:kCIInputImageKey];  
    [filter setValue:[NSNumber numberWithFloat:10.0] forKey:@"inputRadius"];  
    // blur image  
    CIImage *result = [filter valueForKey:kCIOutputImageKey];  
    CGImageRef cgImage = [context createCGImage:result fromRect:[result extent]];  
    UIImage *image = [UIImage imageWithCGImage:cgImage];  
    CGImageRelease(cgImage);  
    self.mainImageView.image = image;