SuspensionManager.SaveAsync C# (CSharp) Method

    static async public Task SaveAsync()
    {
        // Get the output stream for the SessionState file.
        StorageFile file = await ApplicationData.Current.LocalFolder.CreateFileAsync(filename, CreationCollisionOption.ReplaceExisting);
        IRandomAccessStream raStream = await file.OpenAsync(FileAccessMode.ReadWrite);
        using (IOutputStream outStream = raStream)
        {
            // Serialize the Session State.
            DataContractSerializer serializer = new DataContractSerializer(typeof(Dictionary<string, object>), knownTypes_);
            serializer.WriteObject(outStream.AsStreamForWrite(), sessionState_);
            await outStream.FlushAsync();
        }
    }

        protected override async void OnSuspending(object sender, Windows.ApplicationModel.SuspendingEventArgs e)
        {
            var deferral = e.SuspendingOperation.GetDeferral();
            await SuspensionManager.SaveAsync();

            deferral.Complete();
        }