xamarin.android – 升级到6.0版后,MvvmCross App无法启动
2019年05月18日
作者：佚名
我将我的应用程序升级到MvvmCross 6.0版.现在它可以进入启动画面并且不做任何其他事情.通过查看控制台,我可以看到服务正在启动.这是我的app.cs：
public class App : MvxApplication
{
public override void Initialize()
{
MPS.ApplicationName = Settings.ApplicationName;
EventLog.ApplicationName = Settings.ApplicationName;
BlobCache.ApplicationName = Settings.ApplicationName;
CreatableTypes()
.EndingWith("Service")
.AsInterfaces()
.RegisterAsLazySingleton();
CreatableTypes()
.EndingWith("Singleton")
.AsInterfaces()
.RegisterAsSingleton();
//RegisterAppStart(new CustomAppStart());
//RegisterNavigationServiceAppStart<LoginViewModel>();
RegisterAppStart<LoginViewModel>();
}
}
这是非常基本的.我已经转换为新的导航系统因此RegisterNavigationServiceAppStart.那将不再解决,所以我回到了直接的RegisterAppStart.启动画面出现然后停止.如果重要,splashscreen.cs如下：
[Activity(
Label = "@string/ApplicationName",MainLauncher = true,Icon = "@drawable/icon",Theme = "@style/Theme.Splash",NoHistory = true)]
//,ScreenOrientation = ScreenOrientation.Landscape)]
public class SplashScreen : MvxSplashScreenActivity
{
public SplashScreen()
: base(Resource.Layout.SplashScreen)
{
}
}
这很香草,但我知道事情已经发生了变化.我的setup.cs如下：
public class Setup : MvxAndroidSetup
{
//public Setup(Context applicationContext)
// : base(applicationContext)
//{
//}
protected override IMvxApplication CreateApp()
{
return new App();
}
//protected override IMvxTrace CreateDebugTrace()
//{
// return new DebugTrace();
//}
protected override IMvxAndroidViewPresenter CreateViewPresenter()
{
return new MvxAppCompatViewPresenter(AndroidViewAssemblies);
}
protected override void FillValueConverters(IMvxValueConverterRegistry registry)
{
base.FillValueConverters(registry);
registry.AddOrOverwrite("DateToStringConverter",new DateToStringConverter());
registry.AddOrOverwrite("FloatToStringConverter",new FloatToStringConverter());
registry.AddOrOverwrite("DecimalToStringConverter",new DecimalToStringConverter());
registry.AddOrOverwrite("BoolToViewStatesConverter",new BoolToViewStatesValueConverter());
registry.AddOrOverwrite("ShipmentToOriginConverter",new ShipmentToOriginConverter());
registry.AddOrOverwrite("ShipmentToDestinationConverter",new ShipmentToDestinationConverter());
//registry.AddOrOverwrite("CustomName2",new AnotherVerySpecialValueConverter("Summer"));
}
protected override void FillTargetFactories(MvvmCross.Binding.Bindings.Target.Construction.IMvxTargetBindingFactoryRegistry registry)
{
base.FillTargetFactories(registry);
registry.RegisterCustomBindingFactory<EditText>("FocusText",textView => new MvxEditTextFocusBinding(textView));
registry.RegisterCustomBindingFactory<TextView>("FocusChange",textView => new MvxTextViewFocusChangeBinding(textView));
//registry.RegisterCustomBindingFactory<MvxSpinner>("ItemSelected",// spinner => new MvxSpinnerItemSelectedBinding(spinner));
}
protected override IEnumerable<Assembly> AndroidViewAssemblies => new List<Assembly>(base.AndroidViewAssemblies)
{
typeof(MvvmCross.Droid.Support.V7.RecyclerView.MvxRecyclerView).Assembly
};
}
我对它做的唯一改变是删除构造函数.根据6.0版的文档,构造函数不再有参数,所以我没有理由调用它.有人可以帮忙吗？
**更新**
我添加了一个MainApplication.cs,如下所示：
[Application]
public class MainApplication : MvxAppCompatApplication<Setup,App>
{
public MainApplication(IntPtr javaReference,JniHandleOwnership transfer) : base(javaReference,transfer)
{
}
}
这让我超越了启动画面,但挂起了LoginViewModel的Initialize.
*日志*
也许这会有所帮助.以下是事件日志条目：
2018-04-17 12:17:06 [TRACE] (MvvmCross.Core.MvxSetup) Setup: Primary start 2018-04-17 12:17:06 [TRACE] (MvvmCross.Core.MvxSetup) Setup: FirstChance start 2018-04-17 12:17:06 [TRACE] (MvvmCross.Core.MvxSetup) Setup: PlatformServices start 2018-04-17 12:17:06 [TRACE] (MvvmCross.Core.MvxSetup) Setup: MvvmCross settings start 2018-04-17 12:17:06 [TRACE] (MvvmCross.Core.MvxSetup) Setup: Singleton Cache start 2018-04-17 12:17:06 [TRACE] (MvvmCross.Core.MvxSetup) Setup: ViewDispatcher start 2018-04-17 12:17:06 [TRACE] (MvvmCross.Core.MvxSetup) Setup: Bootstrap actions 2018-04-17 12:17:07 [TRACE] (MvvmCross.Logging.MvxLog) No view model type finder available - assuming we are looking for a splash screen - returning null 2018-04-17 12:17:07 [TRACE] (MvvmCross.Core.MvxSetup) Setup: StringToTypeParser start 2018-04-17 12:17:07 [TRACE] (MvvmCross.Core.MvxSetup) Setup: CommandHelper start 2018-04-17 12:17:07 [TRACE] (MvvmCross.Core.MvxSetup) Setup: PluginManagerFramework start 2018-04-17 12:17:07 [TRACE] (MvvmCross.Core.MvxSetup) Setup: Create App 2018-04-17 12:17:07 [TRACE] (MvvmCross.Core.MvxSetup) Setup: NavigationService 2018-04-17 12:17:07 [TRACE] (MvvmCross.Core.MvxSetup) Setup: Load navigation routes 2018-04-17 12:17:07 [TRACE] (MvvmCross.Core.MvxSetup) Setup: App start 2018-04-17 12:17:07 [TRACE] (MvvmCross.Core.MvxSetup) Setup: Application Initialize - On background thread 2018-04-17 12:17:08 [TRACE] (MvvmCross.Core.MvxSetup) Setup: ViewModelTypeFinder start 2018-04-17 12:17:08 [TRACE] (MvvmCross.Core.MvxSetup) Setup: ViewsContainer start 2018-04-17 12:17:08 [TRACE] (MvvmCross.Core.MvxSetup) Setup: Views start 2018-04-17 12:17:08 [TRACE] (MvvmCross.Core.MvxSetup) Setup: CommandCollectionBuilder start 2018-04-17 12:17:08 [TRACE] (MvvmCross.Core.MvxSetup) Setup: NavigationSerializer start 2018-04-17 12:17:08 [TRACE] (MvvmCross.Core.MvxSetup) Setup: InpcInterception start 2018-04-17 12:17:08 [TRACE] (MvvmCross.Core.MvxSetup) Setup: InpcInterception start 2018-04-17 12:17:08 [TRACE] (MvvmCross.Core.MvxSetup) Setup: LastChance start 2018-04-17 12:17:08 [TRACE] (MvvmCross.Core.MvxSetup) Setup: Secondary end 2018-04-17 12:17:08 [TRACE] (MvvmCross.Logging.MvxLog) AppStart: Application Startup - On UI thread
我进一步追踪它.它挂在视图模型中的Initialize()上.我创建了一个测试来演示：
public class FirstViewModel : MvxViewModel
{
public FirstViewModel()
{
Task.Run(async () =>
{
var l = await ListDataSource.GetLocations();
var m = l;
});
}
public async override Task Initialize()
{
await base.Initialize();
var l = await ListDataSource.GetLocations();
var m = l;
}
}
如果我在两个var m = l上设置一个断点,它将到达构造函数中的断点,但永远不会到达Initialize中的断点. GetLocations是：
public async static Task<LocationList> GetLocations()
{
ListServiceClient client = NewClient();
LocationList ret = null;
bool TryCache = false;
try
{
//ret = await client.GetLocationListAsync();
ret = await Task<LocationList>.Factory.FromAsync((asyncCallback,asyncState) => client.BeginGetLocationList(asyncCallback,asyncState),(asyncResult) => client.EndGetLocationList(asyncResult),null);
client.Close();
await BlobCache.LocalMachine.InsertObject("Locations",ret,DateTimeOffset.Now.AddDays(Settings.CacheDays));
}
catch (TimeoutException ex)
{
client.Abort();
EventLog.Error(ex.ToString());
TryCache = true;
}
catch (CommunicationException ex)
{
client.Abort();
EventLog.Error(ex.ToString());
TryCache = true;
}
catch (Exception ex)
{
EventLog.Error(ex.ToString());
TryCache = true;
}
if (TryCache)
{
try
{
ret = await BlobCache.LocalMachine.GetObject<LocationList>("Locations");
}
catch (KeyNotFoundException)
{
ret = null;
}
}
return ret;
}
如果在Client.Close()上设置一个断点,如果从构造函数调用它,它将到达那里,但如果从Initialize调用则不会.
解决方法
我的问题是双重的.首先,当您使用Android升级到6.0版时,您现在必须包含MainApplication.cs,如下所示：
[Application]
public class MainApplication : MvxAppCompatApplication<Setup,transfer)
{
}
}
如果没有这个,你将被困在SplashScreen上.其次,您需要知道您显示的第一个ViewModel中的Initialize必须是同步的.正如@Ale_lipa所提到的,一位MvvmCross作者撰写了一篇博客文章,解释了为什么会这样做以及如何处理它.
https://nicksnettravels.builttoroam.com/post/2018/04/19/MvvmCross-Initialize-method-on-the-first-view-model.aspx
简而言之,如果您使用的是SplashScreen,并且您确实需要将第一个ViewModel的Initialize作为Async,则可以按如下方式添加CustomAppStart：
public class CustomMvxAppStart<TViewModel> : MvxAppStart<TViewModel>
where TViewModel : IMvxViewModel
{
public CustomMvxAppStart(IMvxApplication application,IMvxNavigationService navigationService) : base(application,navigationService)
{
}
protected override void NavigateToFirstViewModel(object hint)
{
NavigationService.Navigate<TViewModel>();
}
}
在你的App.cs中,替换你的：
RegisterAppStart<FirstViewModel>();
有：
RegisterCustomAppStart<CustomMvxAppStart<FirstViewModel>>();
这将允许您的第一个Initialize异步.我只确定它适用于Android,并且只有在使用SplashScreen时才有效.
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