AVAssetExportSession卡住（未启动）导出

我试图从照片库导出视频，但是从未执行导出回调。我会定期检查导出进度，进度始终为零。

以下代码可在99.9％的情况下工作，但有时在某些设备上（绝对随机），它会停止工作，只有重新启动iPhone才有帮助。

AVAssetExportSession.Status一直处于waiting状态

class FilesInteractor {
    static func tempDirectoryPath() -> String {
        let documentsPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] as NSString
        return documentsPath.appendingPathComponent("temp") as String
    }

    static func createTempDirectory() {
        if !FileManager.default.fileExists(atPath: tempDirectoryPath()) {
            try? FileManager.default.createDirectory(atPath: tempDirectoryPath(), withIntermediateDirectories: true, attributes: nil)
        }
    }

    static func testVideoURL(name: String, ext: String = "mov") -> URL {
        createTempDirectory()
        let outputURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0].appendingPathComponent("test").appendingPathComponent("\(name).\(ext)", isDirectory: false)

        log.debug("Test video URL: \(outputURL)")

        return outputURL
    }
}

import AVFoundation

let asset = AVAsset()
let outputURL = FilesInteractor.testVideoURL("output")

let exportSession = AVAssetExportSession(asset: asset, presetName: AVAssetExportPreset1280x720)
exportSession?.outputFileType = .mov
exportSession?.outputURL = outputURL

try? FileManager.default.removeItem(at: outputURL)
exportSession?.exportAsynchronously(completionHandler: {
    print("sometimes never calls")
})

其他视频应用程序也冻结（Filto，Videoleap）：