iOS 从相册导出视频到沙盒 笔记

第一种

UIImagePickerController

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info 
{
    [self dismissViewControllerAnimated:YES completion:nil];
    
    NSURL *url = [info objectForKey:UIImagePickerControllerMediaURL];
    NSData *video = [NSData dataWithContentsOfURL:url];
    if (video.length/1024/1024 >100) { // video size is more than 100 M 
        // code goes here 
        return;
    }
    
    NSURL *videoSaveURL = kVideoSavePath;
    AVAsset *asset = [AVAsset assetWithURL:url];
    AVAssetExportSession *exportSession = [[AVAssetExportSession alloc]initWithAsset:asset presetName:AVAssetExportPresetLowQuality];
    exportSession.outputURL = videoSaveURL;
    exportSession.outputFileType = AVFileTypeMPEG4; // mp4
    [exportSession exportAsynchronouslyWithCompletionHandler:^{
        int exportState = exportSession.status;
        switch (exportState) {
            case AVAssetExportSessionStatusFailed: // export failed
                // code goes here
                break;
            case AVAssetExportSessionStatusCompleted: // finish
            {
                // first frame of video
                #if 1
                AVAssetImageGenerator *imgeGenerator = [AVAssetImageGenerator assetImageGeneratorWithAsset:asset];
                imgeGenerator.appliesPreferredTrackTransform = YES;
                CMTime time = CMTimeMakeWithSeconds(0.0, 600);
                NSValue* timeValue = [NSValue valueWithCMTime:time];
                [imgeGenerator generateCGImagesAsynchronouslyForTimes:@[timeValue] completionHandler:^(CMTime requestedTime, CGImageRef  _Nullable image, CMTime actualTime, AVAssetImageGeneratorResult result, NSError * _Nullable error) {
                    // image
                    UIImage *newImage = [UIImage imageWithCGImage:image];
                    // video in sandbox at 'kVideoSavePath'
                    // code...
                }];
                #else
                    AVAssetImageGenerator *generator = [[AVAssetImageGenerator alloc] initWithAsset:asset];
                    generator.appliesPreferredTrackTransform = YES;
                    NSError *error;
                    CGImageRef imageRef = [generator copyCGImageAtTime:CMTimeMake(0, 10) actualTime:NULL error:&error];
                    if (error) {
                        return nil;
                    }
                    UIImage *image = [UIImage imageWithCGImage:imageRef];
                #endif
            }
                break;
            default:
                break;
        }
    }];
}

第二种

PHAsset

    // Option
    PHVideoRequestOptions *option = [[PHVideoRequestOptions alloc] init];
    option.version = PHVideoRequestOptionsVersionCurrent; // default
    option.deliveryMode = PHVideoRequestOptionsDeliveryModeAutomatic; // default
    
    // Manager
    PHImageManager *manager = [PHImageManager defaultManager];
    [manager requestExportSessionForVideo:asset options:option exportPreset:AVAssetExportPresetMediumQuality  resultHandler:^(AVAssetExportSession * _Nullable exportSession, NSDictionary * _Nullable info) {
        
        // Path
        NSString *videoPath = [NSTemporaryDirectory() stringByAppendingPathComponent:@"saved.mp4"];
        NSLog(@"videoPath:%@",videoPath);
        
        // Export
        exportSession.outputURL = [NSURL fileURLWithPath:videoPath];
        exportSession.shouldOptimizeForNetworkUse = NO;
        exportSession.outputFileType = AVFileTypeMPEG4; // mp4
        [exportSession exportAsynchronouslyWithCompletionHandler:^{
            switch ([exportSession status]) {
                case AVAssetExportSessionStatusFailed:{ 
                    // code...
                }break;
                case AVAssetExportSessionStatusCompleted:{
                    // code...
                }break;
                default:
                    break;
            }
        }];
    }];