MvvmLight 无法为键创建控制器

Question

我正在使用 Xamarin iOS 和 Xamarin Android 设计一个跨平台应用程序架构我决定使用 MvvmLight，它看起来不错并且没有隐藏 MVVM 模式的所有内容，很好而且灵活. 虽然在尝试设置和学习如何使用它时一切都开始变得有意义，但我发现自己很难理解为什么会出现以下错误。

Unable to create a controller for key ChartsPage

设置。

在 PCL 我有我的 ViewModel。我有一个 ViewModelLocator 设置。我使用 mvvmlightlibs Nuget 包。

public class ViewModelLocator
    {
        public static readonly string SchedulerPageKey = @"SchedulerPage";
        public static readonly string ChartsPageKey = @"ChartsPage";

        [SuppressMessage("Microsoft.Performance",
            "CA1822:MarkMembersAsStatic",
            Justification = "This non-static member is needed for data binding purposes.")]
        public SchedulerViewModel Scheduler
        {
            get
            {
                return ServiceLocator.Current.GetInstance<SchedulerViewModel>();
            }
        }

        public BizchartsViewModel Bizcharts
        {
            get
            {
                return ServiceLocator.Current.GetInstance<BizchartsViewModel>();
            }
        }

        static ViewModelLocator()
        {
            ServiceLocator.SetLocatorProvider(() => SimpleIoc.Default);

            if (ViewModelBase.IsInDesignModeStatic)
            {
//              Haven't declared something yet
            }
            else
            {
//              Haven't declared something yet
            }

            SimpleIoc.Default.Register<SchedulerViewModel>();
            SimpleIoc.Default.Register<BizchartsViewModel>();
        }
    }

我有一个统一的 iOS 应用程序，它使用大小为类的通用故事板，它有一个初始的 UINavigationViewController SchedulerViewController 并且在 ViewDidLoad 方法中我测试了导航到 BizchartsViewController 延迟3秒。 3 秒后我得到异常。

在 AppDelegate 中。

private static ViewModelLocator _locator;
        public static ViewModelLocator Locator
        {
            get
            {
                if (_locator == null)
                {
                    SimpleIoc.Default.Register<IDialogService, DialogService>();

                    _locator = new ViewModelLocator();
                }

                return _locator;
            }
        }
        public override bool FinishedLaunching(UIApplication app, NSDictionary options)
        {
            ServiceLocator.SetLocatorProvider(() => SimpleIoc.Default);

            var nav = new NavigationService();
            nav.Initialize((UINavigationController)Window.RootViewController);
            nav.Configure(ViewModelLocator.ChartsPageKey, typeof(BizchartsViewController));

            SimpleIoc.Default.Register<INavigationService>(() => nav);

            return true;
        }

SchedulerViewController.

partial class SchedulerViewController : UIViewController
    {
        public SchedulerViewModel Vm {
            get;
            private set;
        }

        public SchedulerViewController (IntPtr handle) : base (handle)
        {
            Vm = AppDelegate.Locator.Scheduler;
        }

        public async override void ViewDidLoad ()
        {
            base.ViewDidLoad ();

            await Task.Delay (3000);
            Vm.NavigateToCharts ();
        }
    }

SchedulerViewModel.

public class SchedulerViewModel : ViewModelBase
    {
        public void NavigateToCharts()
        {
            var nav = ServiceLocator.Current.GetInstance<INavigationService>();
            nav.NavigateTo(ViewModelLocator.ChartsPageKey);
        }
    }

我肯定漏掉了某个地方的细节！！！

Answer 1

如果你仔细阅读博客 post here，它说在 Storyboard 中你应该使用字符串重载而不是 nav.Configure(Key, ViewController) 并始终在 Storyboard ViewController.

中设置 storyboardId 和 restorationId

Note that because we are using a Storyboard, you must make sure to use the Configure(string, string) overload, and NOT the Configure(string, Type) one.

MvvmLight 无法为键创建控制器

MvvmLight unable to create a controller for key

mvvm

xamarin.ios

mvvm-light

ios

xamarin