帶有MVVM Light的WP7項目中引發的UnauthorizedAccessException（無效的跨線程訪問）

Question

我正在使用MVVM light工具箱的Messenger類來傳達WP7應用程序的不同部分。

從我的應用程序類接收消息時，我試圖使視圖進入不同的狀態。 在視圖的代碼背后，我注冊了消息：

Messenger.Default.Register<PageActionMessage>
(
     this,
    (action) => GoToPage(action)
);

並在收到時調用以下方法：

private object GoToPage(PageActionMessage action)
{
    if (action.action == PageAction.TwitterAuthFinished)
    {
        if (IsoStoreHelper.CheckIfAuthorized())
        {
            VisualStateManager.GoToState(this, "TwitterSendPage", true); // The exception is thrown here
        }
     }
}

在我的另一堂課中，消息是通過以下方式廣播的：

var PageMsg = new PageActionMessage()
{
    action = PageAction.TwitterAuthFinished
};
Messenger.Default.Send<PageActionMessage>(PageMsg);

視圖正確接收了此消息，但是在調用VisualStateManager的GoToState方法時，將引發帶有以下跟蹤的UnauthorizedAccessException（無效的跨線程訪問）：

System.UnauthorizedAccessException was unhandled
  Message=Invalid cross-thread access.
 StackTrace:
   at MS.Internal.XcpImports.CheckThread()
   at System.Windows.DependencyObject.GetValueInternal(DependencyProperty dp)
   at System.Windows.FrameworkElement.GetValueInternal(DependencyProperty dp)
   at System.Windows.DependencyObject.GetValue(DependencyProperty dp)
   at System.Windows.Controls.Panel.get_Children()
   at MS.Internal.XcpImports.CheckThread()
   at MS.Internal.XcpImports.Control_GetImplementationRoot(Control control)
   at System.Windows.Controls.Control.get_ImplementationRoot()
   at System.Windows.VisualStateManager.GoToState(Control control, String stateName, Boolean useTransitions)
   at KidsBook.MainPage.GoToPage(PageActionMessage action)
   at KidsBook.MainPage.<.ctor>b__0(PageActionMessage action)
   at GalaSoft.MvvmLight.Helpers.WeakAction`1.Execute(PageActionMessage parameter)
   at GalaSoft.MvvmLight.Helpers.WeakAction`1.ExecuteWithObject(Object parameter)
   at GalaSoft.MvvmLight.Messaging.Messenger.SendToList[TMessage](PageActionMessage message, IEnumerable`1 list, Type messageTargetType, Object token)
   at GalaSoft.MvvmLight.Messaging.Messenger.SendToTargetOrType[TMessage](PageActionMessage message, Type messageTargetType, Object token)
   at GalaSoft.MvvmLight.Messaging.Messenger.Send[TMessage](PageActionMessage message)
   at KidsBook.Twitter.OAuthClient.GetResponse(IAsyncResult result)
   at System.Net.Browser.ClientHttpWebRequest.<>c__DisplayClassa.<InvokeGetResponseCallback>b__8(Object state2)
   at System.Threading.ThreadPool.WorkItem.WaitCallback_Context(Object state)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadPool.WorkItem.doWork(Object o)
   at System.Threading.Timer.ring()

這是什么原因 提前致謝！

Answer 1

這是我的解決方案：

http://wp8xp.blogspot.com.es/2013/02/llamadas-asincronas-internet-haciendo.html

Deployment.Current.Dispatcher.BeginInvoke(() =>
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            });

Answer 2

使用MVVVMLight，您可以使用DispatcherHelper來確保代碼在UI線程上運行（您的問題）。
例如

DispatcherHelper.CheckBeginInvokeOnUI(YOUR-ACTION);