如何在objective-c中访问AVMediaSelectionKeyValueOption的属性？

所以我正在使用带有字幕轨道的视频,我正在尝试访问每个字幕的名称和语言代码以显示在菜单中.目前我在做：

AVMediaSelectionGroup *selectionGroup = [self.currentAsset mediaSelectionGroupForMediaCharacteristic:AVMediaCharacteristicLegible];
NSArray *subtitles = selectionGroup.options;
self.subtitlesOptions = [NSMutableArray arrayWithObject:@{ @"label": @"Off",@"value": @"off" }];

for(AVMediaSelectionoption *track in subtitles) {
    Nsstring *title = track.displayName; // This isn't right
    Nsstring *language = track.locale.localeIdentifier;
    [self.subtitlesOptions addobject:@{ @"label":title,@"value":language }];
}

当我打印每个轨道对象时,我会得到类似下面的内容.

<AVMediaSelectionkeyvalueOption: 0x171c79c40,language = engcc,mediaType = 'sbtl',title = English Closed Captions>

我可以正确地获得语言,但问题是displayName与title无关,在这种情况下它实际上返回“engcc”而不是“English Closed Captions”.有没有办法获得头衔？

解决方法

我为你的问题找到了这个解决方案.工作正常.希望这会有所帮助.

for(AVMediaSelectionoption *track in subtitles) {
                Nsstring *language = nil;
                NSArray *contents = [AVMetadataItem MetadataItemsFromArray:[mediaSelectionoption commonMetadata] withKey:AVMetadataCommonKeyTitle keySpace:AVMetadataKeySpaceCommon];
                if ([contents count] > 0)
                {

                    NSArray *titlesForPreferredLanguages = [AVMetadataItem MetadataItemsFromArray:contents filteredAndSortedAccordingToPreferredLanguages:[NSLocale preferredLanguages]];
                    if ([titlesForPreferredLanguages count] > 0)
                    {
                        language = [[titlesForPreferredLanguages objectAtIndex:0] extendedLanguageTag];
                    }

                    if (language == nil)
                    {
                        language = [[contents objectAtIndex:0] extendedLanguageTag];
                    }
                }

    }