public class MainPageviewmodel : Screen {
  private DateTime StartActivity = DateTime.MinValue;

  public ObservableCollection<Activityviewmodel> Items { get; set; }

  public MainPageviewmodel(INavigationService navigationService) {
    this.Items = new ObservableCollection<Activityviewmodel>();
  }

  public void AddActivity(string activityName) {
    if (this.Items.Count == 0) {
      this.Items.Add(new Activityviewmodel() { 
        Activity = activityName,Duration = 0 
      });

      StartActivity = DateTime.Now;
      }
    else {
      this.Items[this.Items.Count - 1].Duration = 10;
      this.Items.Add(new Activityviewmodel() { 
        Activity = activityName,Duration = 0 
      });

      StartActivity = DateTime.Now;
    }
  }
}

添加新项目非常有效.

但是,在逻辑删除后应用程序激活时,来自项目的数据无法恢复.尝试为我的viewmodel创建StorageHandler.没有帮助.我做错了什么？

public class MainPageviewmodelStorage : StorageHandler<MainPageviewmodel> {
  public override void Configure() {
    Property(x => x.Items)
        .InAppSettings()
        .RestoreAfterActivation();
  }
}

另外,尝试为类和属性添加[SurviveTombstone],但Visual Studio不知道该属性.

public class Activityviewmodel : PropertyChangedBase {
  private string _activity;
  public string Activity {
    get {
      return _activity;
    }
    set {
      if (value != _activity) {
        _activity = value;
        NotifyOfPropertyChange(() => Activity);
      }
    }
  }

  private double _duration;
  public double Duration {
    get {
      return _duration;
    }
    set {
      if (value != _duration) {
        _duration = value;
        NotifyOfPropertyChange(() => Duration);
      }
    }
  }
}