如何使用IoC构造函数注入（MvvmCross（MvvmCross.Platform.Exceptions.MvxIoCResolveException））

Question

所以我还是MVVM（MvvmCross）/ Android的新手。所以如果我正在做一些非常愚蠢的事情，请道歉。

我一直在追踪Stuart Lodge在Nv 9视频上的“MvxGeoLocation”和“IMvxMessenger”，我确信我一直在追随它完美，但我不知道我要出错的地方。

但是我的应用程序无法解析构造函数的接口。

App.cs：

public override void Initialize() 
{ 
    CreatableTypes() 
     .EndingWith("Service") 
     .AsInterfaces() 
     .RegisterAsLazySingleton(); 

    RegisterAppStart<ViewModels.MainViewModel>(); 
} 

MainViewModel.cs：

public MainViewModel(ILocationService locationService, IMvxMessenger messenger) 
{ 
    _subscriptionToken = messenger.Subscribe<LocationMessage>(OnLocationMessage); 
} 

LocationService.cs：

Public class LocationService : ILocationService 
{ 
    private readonly MvxLocationWatcher _locationWatcher; 
    private readonly IMvxMessenger _messenger; 

    public LocationService(MvxLocationWatcher locationWatcher, IMvxMessenger messenger) 
    { 
     _locationWatcher = locationWatcher; 
     _messenger = messenger; 
     if (!_locationWatcher.Started) _locationWatcher.Start(new MvxLocationOptions(), OnLocation, OnError); 
    } 

    private void OnLocation(MvxGeoLocation location) 
    { 
     System.Diagnostics.Debug.WriteLine(location.Coordinates.Longitude.ToString(), location.Coordinates.Latitude); 
     var message = new LocationMessage(this, location.Coordinates.Longitude, location.Coordinates.Latitude); 
     _messenger.Publish(message); 
    } 

    public void CustomLocation(double lng, double lat) 
    { 
     var message = new LocationMessage(this, lng, lat); 
     _messenger.Publish(message); 
    } 

    private void OnError(MvxLocationError error) 
    { 
     Mvx.Error(error.Code.ToString()); 
    } 
} 

public class LocationMessage : MvxMessage 
{ 
    public LocationMessage(object sender, double lng, double lat) : base(sender) 
    { 
     Lng = lng; 
     Lat = lat; 
    } 

    public double Lng { get; private set; } 
    public double Lat { get; private set; } 
} 

现在ILocationService接口是空的。由于IoC的原因，它在那里。现在，当我运行该应用程序时，它在“base.OnCreate（bundle）;”的MainView Activity上崩溃。

现在在重写InitializeIoC方法，我什至不能做“Mvx.RegisterSingleton（new LocationService（））;”因为我需要给出我显然不能做的论据。我甚至试图使用“Mvx.IocConstruct（）;”，但我意识到这将无法正常工作，因为MvvmCross会自动执行此操作。

---

所以错误消息：

无法构造和定位MvxDefaultViewModelLocator初始化视图模型类型Core.ViewModels.MainViewModel - 检查的InnerException获取更多信息

的InnerException：

{MvvmCross.Platform.Exceptions.MvxException：问题创造型的视图模型MainViewModel ---> MvvmCross.Platform.Exceptions.MvxIoCResolveException：未能解决在MvvmCross创建Core.ViewModels.MainViewModel 当类型ILocationService的参数locationService参数MvvmCross.Platform中的C：\ projects \ mvvmcross \ MvvmCross \ Platform \ Platform \ IoC \ MvxSimpleIoCContainer.cs中的.Platform.IoC.MvxSimpleIoCContainer.GetIoCParameterValues（System.Type类型，System.Reflection.ConstructorInfo firstConstructor）[0x00036]：502 MvvmCross.Platform.Mvx.IocConstruct（System.Type t）中的.IoC.MvxSimpleIoCContainer.IoCConstruct（System.Type类型）[0x0002c]位于C：\ projects \ mvvmcross \ MvvmCross \ Platform \ Platform \ IoC \ MvxSimpleIoCContainer.cs中：312 ）C：\ projects \ mvvmcross \ MvvmCross \ Platform \ Platform \ Mvx.cs中的[0x00006]：1在C：\ projects \ mvvmcross \ MvvmCross \ Core中的[0x00000]中的MvvmCross.Core.ViewModels.MvxDefaultViewModelLocator.Load（System.Type viewModelType，MvvmCross.Core.ViewModels.IMvxBundle parameterValues，MvvmCross.Core.ViewModels.IMvxBundle savedState）上的69 \ Core \ ViewModels \ MvxDefaultViewModelLocator.cs：33 ---内部异常堆栈跟踪结束--- at MvvmCross.Core.ViewModels.MvxDefaultViewModelLocator.Load（System.Type viewModelType，MvvmCross.Core.ViewModels.IMvxCundle parameterValues，MvvmCross .Core.ViewModels。IMvxBundle savedState）[0x0000f]位于MvvmCross.Core.ViewModels.MvxViewModelLoader.LoadViewModel（MvvmCross.Core.ViewModels.MvxViewModelRequest请求，MvvmCross。）中的C：\ projects \ mvvmcross \ MvvmCross \ Core \ Core \ ViewModels \ MvxDefaultViewModelLocator.cs：37 。 Core.ViewModels.IMvxBundle savedState，MvvmCross.Core.ViewModels.IMvxViewModelLocator viewModelLocator）[0x0000e]在C：\项目\ mvvmcross \ MvvmCross \核心\核心\的ViewModels \ MvxViewModelLoader.cs：69}

能提供堆栈跟踪如果需要的话。 那我究竟做错了什么？我花了很多时间试图弄清楚这一点。没有线索。

更新：

添加堆栈跟踪（柜面这是有帮助的）：

“在MvvmCross.Core.ViewModels.MvxViewModelLoader.LoadViewModel（MvvmCross.Core.ViewModels.MvxViewModelRequest要求，MvvmCross.Core .MvvmCross.Core.ViewModels.MvxViewModelLoader中的C：\ projects \ mvvmcross \ MvvmCross \ Core \ Core \ ViewModels \ MvxViewModelLoader.cs：73 \ n中的.ViewModels.IMvxBundle savedState，MvvmCross.Core.ViewModels.IMvxViewModelLocator viewModelLocator）[0x00020]。 LoadViewModel（MvvmCross.Core.ViewModels.MvxViewModelRequest请求，MvvmCross.Core.ViewMod在MvvmCross.Droid.Views.MvxAndroidViewsContainer.ViewModelFromRequest（MvvmCross.Core.ViewModels.MvxViewModelRequest viewModelRequest）中的C：\ projects \ mvvmcross \ MvvmCross \ Core \ Core \ ViewModels \ MvxViewModelLoader.cs：59 \ n中的els.IMvxBundle savedState）[0x00020] ，MvvmCross.Core.ViewModels.IMvxBundle savedState）[0x00006]在C：\ projects \ mvvmcross \ MvvmCross \ Droid \ Droid \ Views \ MvxAndroidViewsContainer.cs：104 \ n在MvvmCross.Droid.Views.MvxAndroidViewsContainer.CreateViewModelFromIntent（Android.Content .Intent intent，MvvmCross.Core.ViewModels.IMvxBundle savedState）[0x00029] in C：\ projects \ mvvmcross \ MvvmCross \ Droid \ Droid \ Views \ MvxAndroidViewsContainer.cs：98 \ n在MvvmCross.Droid.Views.MvxAndroidViewsContainer.Load（ Android.Content.Intent intent，MvvmCross.Core.ViewModels.IMvxBundle savedState，System.Type viewModelTypeHint）在C：\ projects \ mvvmcross \ MvvmCross \ Droid \ Droid \ Views \ MvxAndroidViewsContainer.cs中的[0x00089]：MvvmCross上的67 \ n。 Droid.Views.MvxActivityViewExtensions.LoadViewModel（MvvmCross.Dr在MvvmCross.Droid.Views.MvxActivityViewExtensions + C：\ projects \ mvvmcross \ MvvmCross \ Droid \ Droid \ Views \ MvxActivityViewExtensions.cs中的[0x00065]：oid.Views.IMvxAndroidView androidView，MvvmCross.Core.ViewModels.IMvxBundle savedState）在MvvmCross.Core.Views.MvxViewExtensionMethods.OnViewCreate（MvvmCross.Core.Views。）中的C：\ projects \ mvvmcross \ MvvmCross \ Droid \ Droid \ Views \ MvxActivityViewExtensions.cs：50 \ n中的c__DisplayClass1_0.b__1（）[0x00000] IMvxView视图，System.Func 1[TResult] viewModelLoader) [0x00012] in C:\\projects\\mvvmcross\\MvvmCross\\Core\\Core\\Views\\MvxViewExtensionMethods.cs:28 \n at MvvmCross.Droid.Views.MvxActivityViewExtensions.OnViewCreate (MvvmCross.Droid.Views.IMvxAndroidView androidView, Android.OS.Bundle bundle) [0x00068] in C:\\projects\\mvvmcross\\MvvmCross\\Droid\\Droid\\Views\\MvxActivityViewExtensions.cs:50 \n at MvvmCross.Droid.Views.MvxActivityAdapter.EventSourceOnCreateCalled (System.Object sender, MvvmCross.Platform.Core.MvxValueEventArgs 1 [T] eventArgs）[0x00000]在C：\ projects \ mvvmcross \ MvvmCross \ Droid \ Droid \ Views \ MvxActivityAdapter.cs中：80 \ n at（wrapper delegate-invoke）System.EventHandler 1[MvvmCross.Platform.Core.MvxValueEventArgs 1 [Android.OS.Bundle]]：invoke_void_object_TEventArgs（object，MvvmCross.Platform.Core.MvxValueEventArgs 1<Android.OS.Bundle>)\n at MvvmCross.Platform.Core.MvxDelegateExtensionMethods.Raise[T] (System.EventHandler 1 [TEventArgs] eventHandler，System.Object sender，T value）[0x00000]位于C：\ projects \ mvvmcross \ MvvmCross \ Platform \ Platform \ Core \ MvxDelegateExtensionMethods.cs：21 \ n MvvmCross.Player上的MvvmCross.Platform.Droid.Views.MvxEventSourceActivity.OnCreate（Android.OS.Bundle包）在C：\ projects \ mvvmcross \ MvvmCross \ Platform \ Droid \ Views \ MvxEventSourceActivity.cs中为[0x00014]：34 \ n .Views.MvxActivity.OnCreate（Android.OS.Bundle包）[C：\ projects \ mvvmcross \ MvvmCross \ Droid \ Droid \ Views \ MvxActivity.cs中的[0x00000]：Droid.Views.MainView.OnCreate（Android .OS.Bundle包）[0x00001]位于/Users/jaydeephasmukhlal/Projects/LocationMessengerTest/Droid/Views/MainView.cs:13/n at Android.App.Activity.n_OnCreate_Landroid_os_Bundle_（System.IntPtr jnienv，System.IntPtr native__this，System .IntPtr native_savedInstanceState）[0x0000f]在：0 \ n在（包装纸动态方法）System.Object的：e63afbc8-7ae5-4091-981d-084af38f92fc（IntPtr的，IntPtr的，IntPtr的）”

Answer 1

好吧，我终于得到了从我的资深同事的帮助，发现了愚蠢的错误我犯了。我的界面类ILocationService实际上是一个类而不是一个接口。

实施例的ILocationService是：

public class ILocationService 
{ 
} 

代替：

public interface ILocationService 
{ 
} 

因此，改变类接口解决了这个问题。这是它未能初始化ILocationService的原因。

Answer 2

正在使用的在你的012中的具体类型构造函数MvxLocationWatcher。这应该是IMvxLocationWatcher，然后IoC将为您注入基于平台的具体类（请记住在所有平台中安装位置插件）。您可以查看MvvmCross Location Plugin docs了解更多信息。

开关这样的：

public LocationService(MvxLocationWatcher locationWatcher, IMvxMessenger messenger) 

这样：

public LocationService(IMvxLocationWatcher watcher, IMvxMessenger messenger)