多线程显示动画

Question

我做了一个 动画，在进程开始的时候启动，在进程结束的时候停止，开始的时候显示正确，当在timer里面停止的时候 anmi->Stop()时不执行也不出错，如何停止动画？ 代码如下：

bool MainPage::GetData(){

      if (CoreApplication::Properties->HasKey("WaitAnim")){
          auto wa = safe_cast<Windows::UI::Xaml::Media::Animation::Storyboard^>(CoreApplication::Properties->Lookup("WaitAnim"));
          wa->Begin();
      }
      auto timerDelegate = [this](Windows::System::Threading::ThreadPoolTimer^ timer)
      {
             auto uiDelegate = [this]()
             {
               ...
             };
              Dispatcher->RunAsync(Windows::UI::Core::CoreDispatcherPriority::Normal, ref new Windows::UI::Core::DispatchedHandler(uiDelegate));
               if (CoreApplication::Properties->HasKey("NotifyEnd"))
               {
                      timer->Cancel();
                      if (CoreApplication::Properties->HasKey("WaitAnim"))
                      {
                             auto anim = safe_cast<Windows::UI::Xaml::Media::Animation::Storyboard^>(CoreApplication::Properties->Lookup("WaitAnim"));
                              anim->Stop();
                       }
                }
       };
       DecoderData();
}