图片高斯模糊

   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;