从文档目录中获取已保存的video以在iOS中查看

我正在生成video并保存到CameraRoll，在这里我需要将video提取到我生成并保存在Camera Roll中的下一个视图。希望有人帮忙。我没有得到正确的跟随。实际上我正在创建并使用此代码保存video

NSError *error = nil; NSFileManager *fileMgr = [NSFileManager defaultManager]; NSString *documentsDirectory = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"]; NSString *videoOutputPath = [documentsDirectory stringByAppendingPathComponent:@"test_output.mp4"]; if ([fileMgr removeItemAtPath:videoOutputPath error:&error] != YES) NSLog(@"Unable to delete file: %@", [error localizedDescription]); CGSize imageSize = CGSizeMake(400, 200); NSUInteger fps = 30; NSArray* imagePaths = [[NSBundle mainBundle] pathsForResourcesOfType:@"jpg" inDirectory:nil]; self.chosenImages = [[NSMutableArray alloc] initWithCapacity:imagePaths.count]; NSLog(@"-->imageArray.count= %i", self.chosenImages.count); for (NSString* path in imagePaths) { [self.chosenImages addObject:[UIImage imageWithContentsOfFile:path]]; } NSLog(@"Start building video from defined frames."); AVAssetWriter *videoWriter = [[AVAssetWriter alloc] initWithURL: [NSURL fileURLWithPath:videoOutputPath] fileType:AVFileTypeQuickTimeMovie error:&error]; NSParameterAssert(videoWriter); NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys: AVVideoCodecH264, AVVideoCodecKey, [NSNumber numberWithInt:imageSize.width], AVVideoWidthKey, [NSNumber numberWithInt:imageSize.height], AVVideoHeightKey, nil]; AVAssetWriterInput* videoWriterInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo outputSettings:videoSettings]; AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdapto assetWriterInputPixelBufferAdaptorWithAssetWriterInput:videoWriterInput sourcePixelBufferAttributes:nil]; NSParameterAssert(videoWriterInput); NSParameterAssert([videoWriter canAddInput:videoWriterInput]); videoWriterInput.expectsMediaDataInRealTime = YES; [videoWriter addInput:videoWriterInput]; [videoWriter startWriting]; [videoWriter startSessionAtSourceTime:kCMTimeZero]; CVPixelBufferRef buffer = NULL; int frameCount = 0; double numberOfSecondsPerFrame = 6; double frameDuration = fps * numberOfSecondsPerFrame; for(UIImage * img in self.chosenImages) { //UIImage * img = frm._imageFrame; buffer = [self pixelBufferFromCGImage:[img CGImage]]; BOOL append_ok = NO; int j = 0; while (!append_ok && j %@", outputFilePath);