我有带有项目（ObservableCollection）的 MainPageViewModel。在此页面上，我还有一个按钮，用于向 Items 添加新项目。
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;
}
}
}
添加新项目非常完美。
但是当应用程序在墓碑后激活时，来自项目的数据不会恢复。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();
}
}
还可以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);
}
}
}
}