【发布时间】：2019-04-22 22:41:35
【问题描述】：
问题陈述 我想创建一个 contentview 用户控件，它有自己的视图模型，可以在多个内容页面中使用。
以下实现中的问题 我已经扩展了我的 App.xaml.cs，如下所述。但是，一旦导航从具有 contentview 用户控件的 contentpage 工作，但如果我再次导航到该页面，导航将不起作用。只是为了添加它， view.Parent 在下面的代码中也为空。
请帮忙。
using OEP.Views;
using Prism;
using Prism.Common;
using Prism.Ioc;
using Prism.Mvvm;
using Prism.Navigation;
using Prism.Unity;
using Unity.Resolution;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;
[assembly: XamlCompilation(XamlCompilationOptions.Compile)]
namespace OEP
{
public partial class App : PrismApplication
{
public App() : this(null) { }
public App(IPlatformInitializer initializer) : base(initializer) { }
protected override async void OnInitialized()
{
InitializeComponent();
//await NavigationService.NavigateAsync("NewOrderPage");
await NavigationService.NavigateAsync("LoginPage");
//await NavigationService.NavigateAsync("HomePage");
}
protected override void RegisterTypes(IContainerRegistry containerRegistry)
{
containerRegistry.RegisterForNavigation<LoginPage>();
containerRegistry.RegisterForNavigation<ForgotPasswordPage>();
containerRegistry.RegisterForNavigation<HomePage>();
containerRegistry.RegisterForNavigation<CustomerDetailsPage>();
containerRegistry.RegisterForNavigation<NewOrderPage>();
//Container.Resolve<HomePageCustomersUserControl>("Customers");
//containerRegistry.Register<HomePageCustomersUserControl, HomePageCustomersUserControlViewModel>();
//ViewModelLocationProvider.Register<HomePageCustomersUserControl>(() => Container.Resolve<HomePageCustomersUserControlViewModel>());
}
protected override void ConfigureViewModelLocator()
{
ViewModelLocationProvider.SetDefaultViewModelFactory((view, type) =>
{
Page page = null;
switch (view)
{
case Page page1:
page = page1;
break;
case Element customView:
page = GetPageFromElement(customView);
// Existing parameter with the Page
break;
}
var navService = CreateNavigationService(page);
ParameterOverrides overrides = new ParameterOverrides
{
{ "navigationService", navService }
};
return Container.GetContainer().Resolve(type, type.GetType().Name, overrides);
});
}
// Currently exists
protected INavigationService CreateNavigationService(Page page)
{
var navigationService = NavigationService;
((IPageAware)navigationService).Page = page;
return navigationService;
}
protected INavigationService CreateNavigationService(object view)
{
switch (view)
{
case Page page:
return CreateNavigationService(page);
case Element element:
var parentPage = GetPageFromElement(element);
if (parentPage == null)
{
return null;
}
return CreateNavigationService(parentPage);
default:
return null;
}
}
private Page GetPageFromElement(Element view)
{
switch (view.Parent)
{
case Page page:
return page;
case null:
return null;
default:
return GetPageFromElement(view.Parent);
}
}
protected override void OnStart()
{
// Handle when your app starts
}
protected override void OnSleep()
{
// Handle when your app sleeps
}
protected override void OnResume()
{
// Handle when your app resumes
}
}
}
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标签： xamarin.forms prism