private async void createLogFileAsync() { Windows.Storage.StorageFolder storageFolder = Windows.Storage.ApplicationData.Current.LocalFolder; var messageDialog = new MessageDialog(storageFolder.ToString()); Windows.Storage.StorageFile sampleFile = await storageFolder.CreateFileAsync("log.txt", Windows.Storage.CreationCollisionOption.GenerateUniqueName); stream = await sampleFile.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite); outputStream = stream.GetOutputStreamAt(0); dataWriter = new Windows.Storage.Streams.DataWriter(outputStream); }