IntentFilter，开放表单视图

Question

我正在浏览器中进行用户身份验证。

成功通过身份验证后，浏览器将关闭，AndroidMainActivity.OnCreate()将被执行。但是，应用程序显示空白屏幕，就像没有加载视图/页面一样。我从MVVMCross (MvvmCross.Logging.MvxLog)获得这个日志，没有为LoadViewModel中的AndroidMainActivity指定ViewModel类。

所以现在看来，我应该导航到一些表格页，也许？但是导航对我没有任何帮助。也许我应该以不同的方式去做它，但是我找不到关于如何去做的任何文章或例子。

我现在就是这么做的：

    [Activity(MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation)]
    [IntentFilter([] { Intent.ActionView }, Categories = new[] { Intent.CategoryDefault, Intent.CategoryBrowsable }, DataScheme = GdspScheme.SCHEME)]
    public class AndroidMainActivity : MvxFormsAppCompatActivity<AndroidSetup, MainApplication, App>
    {
        protected override void OnCreate(Bundle bundle)
        {
            if (Intent.Data != null)
            {
                // user authenticated

                Xamarin.Forms.Application.Current.MainPage.Navigation.PushAsync(new NavigationPage(new FormsView()));
            }
        }
    }

Answer 1

我终于在MvvmCross文档中找到了解决方案：https://www.mvvmcross.com/documentation/advanced/customizing-appstart?scroll=100

public class App : MvxApplication
{
    public override void Initialize()
    {       
        RegisterCustomAppStart<AppStart>();
    }
}




    public class AppStart : MvxAppStart
{
    private readonly IAuthenticationService _authenticationService;

    public MvxAppStart(IMvxApplication application, IMvxNavigationService navigationService, IAuthenticationService authenticationService) : base(application, navigationService)
    {
        _authenticationService = authenticationService;
    }

    protected override void NavigateToFirstViewModel(object hint = null)
    {
        try
        {
            // You need to run Task sync otherwise code would continue before completing.
            var tcs = new TaskCompletionSource<bool>();
            Task.Run(async () => tcs.SetResult(await _authenticationService.IsAuthenticated()));
            var isAuthenticated = tcs.Task.Result;

            if (isAuthenticated)
            {
                //You need to Navigate sync so the screen is added to the root before continuing.
                NavigationService.Navigate<HomeViewModel>().GetAwaiter().GetResult();
            }
            else
            {
                NavigationService.Navigate<LoginViewModel>().GetAwaiter().GetResult();
            }
        }
        catch (System.Exception exception)
        {
            throw exception.MvxWrap("Problem navigating to ViewModel {0}", typeof(TViewModel).Name);
        }
    }
}

Answer 2

当然，您应该在Forms项目中调用这一行。

您可以使用MessagingCenter

在MainActivity

if (Intent.Data != null)
{
  // user authenticated
  MessagingCenter.Send<Object>(this, "authenticatedFinished");
  
}

在窗体->the构造函数中的MainPage

public xxxMainPage()
{
  //...
  MessagingCenter.Subscribe<Object>(this, "authenticatedFinished", () =>
  {   
      Navigation.PushAsync(new NavigationPage(new FormsView()));
                        
  });
}