CMSampleBufferRef=>UIImage

- (UIImage *)imageConvert:(CMSampleBufferRef)sampleBuffer{      if (CMSampleBufferIsValid(sampleBuffer)) {        return nil;    }    CVPixelBufferRef pixelBuffer = (CVPixelBufferRef)CMSampleBufferGetImageBuffer(sampleBuffer);        CIImage *ciImage = [CIImage imageWithCVPixelBuffer:pixelBuffer];        UIImage *image = [UIImage imageWithCIImage:ciImage];    return image;}