c# - 系统.MissingMethodException : Method 'MvvmCross.Droid.Views.MvxAndroidViewPresenter..ctor' not found

Question

我创建了设置:MvxAndroidSetup

 public class Setup : MvxAndroidSetup
{
    public Setup(Context applicationContext)
        : base(applicationContext)
    {
    }

    protected override IMvxApplication CreateApp()
    {
        return new App();
    }

    protected override IEnumerable<Assembly> AndroidViewAssemblies => 
    new List<Assembly>(base.AndroidViewAssemblies)
    {
        typeof(Android.Support.Design.Widget.NavigationView).Assembly,
        typeof(Android.Support.Design.Widget.FloatingActionButton).Assembly,
        typeof(Android.Support.V7.Widget.Toolbar).Assembly,
        typeof(Android.Support.V4.Widget.DrawerLayout).Assembly,
        typeof(Android.Support.V4.View.ViewPager).Assembly,
        typeof(MvvmCross.Droid.Support.V7.RecyclerView.MvxRecyclerView).Assembly
    };

    /// <summary>
    /// This is very important to override. The default view presenter does not know how to show fragments!
    /// </summary>
    protected override IMvxAndroidViewPresenter CreateViewPresenter()
    {
        var mvxFragmentsPresenter = new MvxFragmentsPresenter(AndroidViewAssemblies);
        Mvx.RegisterSingleton<IMvxAndroidViewPresenter>(mvxFragmentsPresenter);
        return mvxFragmentsPresenter;
    }
}

我使用 mvvmscross 版本 5.2.1我在行代码 var mvxFragmentsPresenter = new MvxFragmentsPresenter(AndroidViewAssemblies); 中遇到问题。运行项目时 mac 中的 Visual Studio 2017 通知:

System.MissingMethodException: Method 'MvvmCross.Droid.Views.MvxAndroidViewPresenter..ctor' not found.
  at VietOrder.Droid.Setup.CreateViewPresenter () [0x00001] in /Volumes/Data/Dev/VietOrder/Xamarin/VietOrder/VietOrder.Droid/Setup.cs:46
  at MvvmCross.Droid.Platform.MvxAndroidSetup.CreateViewDispatcher () [0x00000] in C:\projects\mvvmcross\MvvmCross\Droid\Droid\Platform\MvxAndroidSetup.cs:124
  at MvvmCross.Core.Platform.MvxSetup.InitializeViewDispatcher () [0x00000] in C:\projects\mvvmcross\MvvmCross\Core\Core\Platform\MvxSetup.cs:260
  at MvvmCross.Core.Platform.MvxSetup.InitializeSecondary () [0x000f8] in C:\projects\mvvmcross\MvvmCross\Core\Core\Platform\MvxSetup.cs:91
  at MvvmCross.Droid.Platform.MvxAndroidSetupSingleton.<InitializeFromSplashScreen>b__7_0 (System.Object ignored) [0x00000] in C:\projects\mvvmcross\MvvmCross\Droid\Droid\Platform\MvxAndroidSetupSingleton.cs:92
  at System.Threading.QueueUserWorkItemCallback.WaitCallback_Context (System.Object state) [0x00007] in <896ad1d315ca4ba7b117efb8dacaedcf>:0
  at System.Threading.ExecutionContext.RunInternal (System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, System.Object state, System.Boolean preserveSyncCtx) [0x00071] in <896ad1d315ca4ba7b117efb8dacaedcf>:0
  at System.Threading.ExecutionContext.Run (System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, System.Object state, System.Boolean preserveSyncCtx) [0x00000] in <896ad1d315ca4ba7b117efb8dacaedcf>:0
  at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem () [0x00021] in <896ad1d315ca4ba7b117efb8dacaedcf>:0
  at System.Threading.ThreadPoolWorkQueue.Dispatch () [0x00074] in <896ad1d315ca4ba7b117efb8dacaedcf>:0
  at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback () [0x00000] in <896ad1d315ca4ba7b117efb8dacaedcf>:0

谢谢!

Answer 1

我想我已经解决了它，但是从版本 4.4.0 升级到最新的 MvvmCross 版本 (5.3.1) 的漫长旅程已经结束。我将确定完成升级所需的步骤。应该注意的是，在此之前我已经将所有 Xamarin 和其他包更新到最新和最好的，并确保项目编译和运行。此外，我将 Xamarin 本身更新为 4.7.10.22，它带来了对 Android 8.0 的支持(我还没有 iOS 前端)。这是我更新到 MvvmCross 5.3.1 所经历的步骤:

• 将所有 MvvmCross 包升级到 5.3.1
• 删除 MvvmCross.Droid.Shared (4.4.0)
• 添加 MvvmCross.Droid.Support.Core.UI (5.3.1)
• 添加 MvvmCross.Droid.Support.Core.Utils (5.3.1)
• 添加 MvvmCross.Droid.Support.Fragment (5.3.1)

现在回答您的问题，我将我的 Setup 类更改为 MvxAppCompatSetup 的子类。对 MvxAppCompatSetup 的调用更改为简单地创建一个新的 MvxAppCompatViewPresenter()(见下文)并删除 MvvmCross.Droid.Shared.Presenter 的导入:

protected override IMvxAndroidViewPresenter CreateViewPresenter()
{            
   return new MvxAppCompatViewPresenter(AndroidViewAssemblies);
}

此外，由于我使用了一些片段，我需要将它们的属性从 MvxFragment 更改为 MvxFragmentPresentation。最后的更改是将我的主要事件从子类 MvxCachingFragmentCompatActivity 更改为子类 MvxAppCompatActivity。所有这些对我有用，希望对您有所帮助。

附言我仍然需要更改导航以符合新的 NavigationService。