我使用AVAssetwriter和AVAssetExportSession从一组图像创建视频，并成功获取视频并将其保存到文档中。但随机视频导出失败，并显示错误代码-11800出现An Unknown错误。
ExportSessionError: -11800 adn userinfo{
NSLocalizedDescription = "The operation could not be completed";
NSLocalizedFailureReason = "An unknown error occurred (-12124)";
NSUnderlyingError = "Error Domain=NSOSStatusErrorDomain Code=-12124 \"The operation couldn\U2019t be completed. (OSStatus error -12124.)\"";
这是我得到的错误控制台..请帮帮我..谢谢