带有outputFileType m4a的AVAssetExportSession不能在iOS13上运行

Question

我怀疑带有iOS13的Xcode 11无法与带有iOS12.2的Xcode 10.2.1正常工作

我试图将两个音频文件合并为一个音频文件。

下面的代码可以在iOS 12.2上正常运行Xcode 10.2.1，但现在可以在iOS13上正常运行xcode 11

   @objc func applyMergeAudio(){

        playmerge(audio1: Bundle.main.url(forResource: "audio0", withExtension: "mp3")!,audio2: Bundle.main.url(forResource: "Asteroid_Sound", withExtension: "mp3")!)
    }

    func playmerge(audio1: URL, audio2:  URL)
    {
        let composition = AVMutableComposition()
        let compositionAudioTrack1:AVMutableCompositionTrack = composition.addMutableTrack(withMediaType: AVMediaType.audio, preferredTrackID: CMPersistentTrackID())!
        let compositionAudioTrack2:AVMutableCompositionTrack = composition.addMutableTrack(withMediaType: AVMediaType.audio, preferredTrackID: CMPersistentTrackID())!

        let documentDirectoryURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
        let fileDestinationUrl = documentDirectoryURL.appendingPathComponent("resultmerge.m4a")

        let filemanager = FileManager.default
        if (!filemanager.fileExists(atPath: fileDestinationUrl.path))
        {
            do
            {
                try filemanager.removeItem(at: fileDestinationUrl)
            }
            catch let error as NSError
            {
                NSLog("Error: \(error)")
            }
        }

        let avAsset1 = AVURLAsset(url: audio1, options: nil)
        let avAsset2 = AVURLAsset(url: audio2, options: nil)

        var tracks1 = avAsset1.tracks(withMediaType: AVMediaType.audio)
        var tracks2 = avAsset2.tracks(withMediaType: AVMediaType.audio)

        let assetTrack1:AVAssetTrack = tracks1[0]
        let assetTrack2:AVAssetTrack = tracks2[0]

        let duration1: CMTime = assetTrack1.timeRange.duration
        let duration2: CMTime = assetTrack2.timeRange.duration

        let timeRange1 = CMTimeRangeMake(start: CMTime.zero, duration: duration1)
        let timeRange2 = CMTimeRangeMake(start: CMTime.zero, duration: duration2)
        do
        {
            try compositionAudioTrack1.insertTimeRange(timeRange1, of: assetTrack1, at: CMTime.zero)
            try compositionAudioTrack2.insertTimeRange(timeRange2, of: assetTrack2, at: CMTime.zero)
        }
        catch
        {
            print(error)
        }

        //below line force unwarp Version xcode 10.2.1 working fine with iOS12.2. but xcode 11 with iOS13 got crush . .
        let assetExport = AVAssetExportSession(asset: composition, presetName: AVAssetExportPresetAppleM4A)
        assetExport?.outputFileType = AVFileType.m4a
        assetExport?.outputURL = fileDestinationUrl
        assetExport?.exportAsynchronously(completionHandler:
            {
                //xcode 11 with iOS13 not fire this block but xcode 10.2.1 with iOS12.2 working fine.
                print(fileDestinationUrl)
        })
    }

所以您能告诉我任何替代解决方案，或者我错过了什么吗？。

Answer 1

不是太多的答案，但是很难将所有这些作为评论来传达。

[Per Apple，AVAssetExportSession上有一个函数，您可以调用名为allExportPresets()的函数，该函数将输出所有可用的预设。

您也可以用exportPresets(compatibleWith:)呼叫AVAsset以查找与该特定资产兼容的资产。

当我用iOS 12]呼叫allExportPresets()时，得到以下输出：

[“” AVAssetExportPreset1920x1080“，” AVAssetExportPresetLowQuality“，“ AVAssetExportPresetAppleM4A”，“ AVAssetExportPresetHEVCHighestQuality”，“ AVAssetExportPreset640x480”，“ AVAssetExportPreset3840x2160”，“ AVAssetExportPresetHEVC3840x2160”，“ AVAssetExportPresetHighestQuality”，“ AVAssetExportPreset1280x720”，“ AVAssetExportPresetMediumQuality”，“ AVAssetExportPreset960x540”，“ AVAssetExportPresetHEVC1920x1080”]

虽然通过iOS 13]调用相同的函数，但得到：

[]

但是，当我在支持页面上查看各种预设时，找不到任何说明已弃用的文档，等等。>>

我稍后可以尝试进行测试，看看是否可以添加到此。

希望现在至少可以提供一些指导。