objective-c - 如何在 objective-c 中访问 AVMediaSelectionKeyValueOption 的属性？

Question

所以我正在处理一个带有字幕轨道的视频，我正在尝试访问每个视频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 track 对象时，我得到类似下面的内容。

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

我可以正确获取语言，但问题是 displayName 与 title 不相关，在这种情况下它实际上返回“engcc”而不是“English”隐藏式字幕”。有什么方法可以得到 title 吗？

Answer 1

我为您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];
                    }
                }

    }