暂停状态处理

当移动到 Suspened 状态时，会有与此事件相关的特殊处理程序：打开“App.xaml.cx”类并查看 App 构造函数 - 有事件处理程序：

public App()
    {
        this.InitializeComponent();
        //Handle suspending operation with event handler:
        this.Suspending += OnSuspending;
    }

现在你可以处理暂停事件：

private Dictionary<string, object> _store = new Dictionary<string, object>();
private readonly string _saveFileName = "store.xml";
private async void OnSuspending(object sender, SuspendingEventArgs e)
    {
        var deferral = e.SuspendingOperation.GetDeferral();
        _store.Add("timestamp", DateTime.Now);
        await SaveStateAsync();
        //TODO: Save application state and stop any background activity
        //Here you can use  await SuspensionManager.SaveAsync();
        //To read more about saving state please refer to below MSDN Blog article:
        //https://blogs.windows.com/buildingapps/2016/04/28/the-lifecycle-of-a-uwp-app/#RqKAKkevsAPIvBUT.97
        deferral.Complete();
    }

    private async Task SaveStateAsync()
    {
        var ms = new MemoryStream();
        var serializer = new DataContractSerializer(typeof(Dictionary<string, object>));
        serializer.WriteObject(ms, _store);

        var file = await ApplicationData.Current.LocalFolder.CreateFileAsync(_saveFileName, CreationCollisionOption.ReplaceExisting);

        using (var fs = await file.OpenStreamForWriteAsync())
        {
            //because we have written to the stream, set the position back to start
            ms.Seek(0, SeekOrigin.Begin);
            await ms.CopyToAsync(fs);
            await fs.FlushAsync();
        }
    }