iPhone：以编程方式压缩录制的视频以共享吗？

Question

在录制视频之前调用相机视图时，我已经实现了叠加视图。pickerController.cameraOverlayView =myOverlay;录制视频并通过电子邮件共享后，可以进行视频录制并将视频保存到“相册”中。如果我将视频质量用作“高质量”，则录制的视频已经变得很大。例如，如果我以高质量录制视频30秒钟，则录制的视频已变为30-40 mb。pickerController.videoQuality = UIImagePickerControllerQualityTypeHigh;我如何编程才能在共享之前压缩高质量的录制视频，就像Apple对内置视频录制器的处理方式一样？请指导我解决此问题。谢谢！更新：这是我最近正在尝试的方法，但仍然没有成功：我想压缩录制的音频，并将它们录制到didFinishPickingMediaWithInfo并将其实际的视频路径本身存储在同一相册中，而不是其他位置。当我从照片库中选取时，我测试了将相同的视频压缩到非常小的尺寸，但是虽然我使用了下面的AVAssetExportSession代码，但是从相机拍摄并通过didFinishPickingMediaWithInfo来的相同视频未压缩。- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{    NSString *mediaType = [info objectForKey:UIImagePickerControllerMediaType];if ([mediaType isEqualToString:(NSString *)kUTTypeMovie]){    NSURL *videoURL = [info objectForKey:UIImagePickerControllerMediaURL];    NSString *urlPath = [videoURL path];    if ([[urlPath lastPathComponent] isEqualToString:@"capturedvideo.MOV"])    {        if (UIVideoAtPathIsCompatibleWithSavedPhotosAlbum (urlPath))        {            [self copyTempVideoToMediaLibrary :urlPath];        }        else        {            NSLog(@"Video Capture Error: Captured video cannot be saved...didFinishPickingMediaWithInfo()");                        }    }           else    {        NSLog(@"Processing soon to saved photos album...else loop of lastPathComponent..didFinishPickingMediaWithInfo()");    }}    [self dismissModalViewControllerAnimated:YES];}- (void)copyTempVideoToMediaLibrary :(NSString *)videoURL {        dispatch_queue_t mainQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);dispatch_async(mainQueue, ^{    ALAssetsLibrary *library = [[[ALAssetsLibrary alloc] init] autorelease];    ALAssetsLibraryWriteVideoCompletionBlock completionBlock = ^(NSURL *assetURL, NSError *error) {        NSLog(@"Saved URL: %@", assetURL);        NSLog(@"Error: %@", error);