iOS模糊效果

- (UIImage *)applyBlurRadius:(CGFloat)radius toImage:(UIImage *)image {     if (radius < 0) radius = 0;     CIContext *context = [CIContext contextWithOptions:nil];     CIImage *inputImage = [CIImage imageWithCGImage:image.CGImage];     CIFilter *filter = [CIFilter filterWithName:@"CIGaussianBlur"];     [filter setValue:inputImage forKey:kCIInputImageKey];     [filter setValue:[NSNumber numberWithFloat:radius] forKey:@"inputRadius"];     CIImage *result = [filter valueForKey:kCIOutputImageKey];     CGImageRef cgImage = [context createCGImage:result fromRect:[inputImage extent]];     UIImage *returnImage = [UIImage imageWithCGImage:cgImage];     CGImageRelease(cgImage);     return returnImage; }