类似微信发送视频的流程

获取视频的本地url或者path，对视频进行获取第一帧图片，然后初始化消息的Model，设置封面

NSString *mediaType = [editingInfo objectForKey: UIImagePickerControllerMediaType];

NSString *videoPath;

NSURL *videoUrl;

if (CFStringCompare ((__bridge CFStringRef) mediaType, kUTTypeMovie, 0) == kCFCompareEqualTo) {

videoUrl = (NSURL*)[editingInfo objectForKey:UIImagePickerControllerMediaURL];

videoPath = [videoUrl path];

AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:videoUrl options:nil];

NSParameterAssert(asset);

AVAssetImageGenerator *assetImageGenerator = [[AVAssetImageGenerator alloc] initWithAsset:asset];

assetImageGenerator.appliesPreferredTrackTransform = YES;

assetImageGenerator.apertureMode = AVAssetImageGeneratorApertureModeEncodedPixels;

CGImageRef thumbnailImageRef = NULL;

CFTimeInterval thumbnailImageTime = 0;

NSError *thumbnailImageGenerationError = nil;

thumbnailImageRef = [assetImageGenerator copyCGImageAtTime:CMTimeMake(thumbnailImageTime, 60) actualTime:NULL error:&thumbnailImageGenerationError;];

if (!thumbnailImageRef)

NSLog(@"thumbnailImageGenerationError %@", thumbnailImageGenerationError);

UIImage *thumbnailImage = thumbnailImageRef ? [[UIImage alloc] initWithCGImage:thumbnailImageRef] : nil;

XHMessage *videoMessage = [[XHMessage alloc] initWithVideoConverPhoto:thumbnailImage videoPath:videoPath videoUrl:nil sender:@"Jack" timestamp:[NSDate date]];

[weakSelf addMessage:videoMessage];

}