我的应用程序崩溃“由于未捕获的异常”NSInternalInconsistencyException“，正在终止应用程序，原因：'从主线程访问布局引擎后，不能从后台线程执行对布局引擎的修改。”
我从网址下载一个mp4文件，当它成功地将文件保存在库中时，它在打印消息时崩溃。

Code crashes after if completed { }

func downloadVideoLinkAndCreateAsset(videoLink: String?) {
    
    DispatchQueue.global(qos: .background).async {
        if let url = URL(string: videoLink ?? ""),
           let urlData = NSData(contentsOf: url) {
            let documentsPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0];
            let filePath="\(documentsPath)/tempFile.mp4"
            DispatchQueue.main.async {
                urlData.write(toFile: filePath, atomically: true)
                PHPhotoLibrary.shared().performChanges({
                    PHAssetChangeRequest.creationRequestForAssetFromVideo(atFileURL: URL(fileURLWithPath: filePath))
                }) { completed, error in
                    if completed {
                        self.removeAllOverlays()
                        print( "Video is Saved in Library")
                    }
                }
            }
        }
    }
    
    
}