具有MVVMLight的Xamarin Android：只有創建視圖層次結構的原始線程才能觸及其視圖

Question

每當我更新已在活動中綁定的ViewModel屬性時，我收到此錯誤。我知道這個錯誤是從另一個線程（不是UI線程）更新的用戶界面相關的，但我無法控制如何MVVMLight做結合...

活動：

private readonly List<Binding> _bindings = new List<Binding>(); 

public PersonViewModel ViewModel 
{ 
    get 
    { 
     return App.Locator.Detail; 
    } 
} 

private TextView _txtName; 
public TextView TxtName 
{ 
    get 
    { 
     return _txtName ?? 
      (_txtName = FindViewById<TextView>(Resource.Id.txtName)); 
    } 
} 

protected async override void OnCreate(Bundle savedInstanceState) 
{ 
    base.OnCreate(savedInstanceState); 
    SetContentView(Resource.Layout.Detail); 

    _bindings.Add(this.SetBinding(
     () => ViewModel.Person.Name, 
     () => TxtName.Text)); 

    await Task.Factory.StartNew(() => { ViewModel.LoadDetailCommand.Execute(null); }); 
} 

視圖模型：

private IDataService _dataService; 

private PersonObj _person; 
public PersonObj Person 
{ 
    get 
    { 
     return _person; 
    } 
    set 
    { 
     Set(ref _person, value); 
    } 
} 

private RelayCommand _loadDetailCommand; 
public RelayCommand LoadDetailCommand 
{ 
    get 
    { 
     return _loadDetailCommand 
       ?? (_loadDetailCommand = new RelayCommand(
        async() => 
        { 
         await LoadDataAsync(); 
        })); 
    } 
} 

public PersonViewModel(IDataService dataService) 
{ 
    _dataService = dataService; 
} 

private async Task LoadDataAsync() 
{ 
    try 
    { 
     Person= await _dataService.GetPerson(0); 
    } 
    catch (Exception ex) 
    { 
     // Exception here!! 
    } 
} 

Answer 1

好，我在ViewModel需要的時候管理它創建任務並等待它，以便我可以捕獲所有可能的例外：

Person = await Task.Run(async() => 
{ 
    var p = await _dataService.GetPerson(0); 
    return p; 
}); 

感謝@xleon的幫助。

Answer 2

我一無所知MVVMLight，但我倒是試圖改變這一行：上

await Task.Factory.StartNew(() => { ViewModel.LoadDetailCommand.Execute(null); }); 

此E：

ViewModel.LoadDetailCommand.Execute(null); 

您shouldn't需要啓動一個新的任務要執行的命令

這一個：

protected async override void OnCreate(Bundle savedInstanceState) 

這一個：

protected override void OnCreate(Bundle savedInstanceState)