UIImageFromSampleBuffer.m

// this is a property in my class because I reuse it

self.coreImageContext = [CIContext contextWithOptions:nil];

// ...

- (UIImage *)UIImageFromSampleBuffer:(CMSampleBufferRef)sampleBuffer {
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
    CIImage *ciImage = [CIImage imageWithCVImageBuffer:imageBuffer];
    CGImageRef cgImage = [self.coreImageContext createCGImage:ciImage fromRect:ciImage.extent];
    UIImage *image = [UIImage imageWithCGImage:cgImage];
    CGImageRelease(cgImage);
    return image;
}