我的Android应用程序中包含以下代码，它基本上使用一页（使用NavigationDrawer）并在中央视图中交换片段。这允许导航在一页而不是多页上进行：
Setup.cs：
protected override IMvxAndroidViewPresenter CreateViewPresenter()
{
var customPresenter = new MvxFragmentsPresenter();
Mvx.RegisterSingleton<IMvxFragmentsPresenter>(customPresenter);
return customPresenter;
}
ShellPage.cs
public class ShellPage : MvxCachingFragmentCompatActivity<ShellPageViewModel>, IMvxFragmentHost
{
.
.
.
public bool Show(MvxViewModelRequest request, Bundle bundle)
{
if (request.ViewModelType == typeof(MenuContentViewModel))
{
ShowFragment(request.ViewModelType.Name, Resource.Id.navigation_frame, bundle);
return true;
}
else
{
ShowFragment(request.ViewModelType.Name, Resource.Id.content_frame, bundle, true);
return true;
}
}
public bool Close(IMvxViewModel viewModel)
{
CloseFragment(viewModel.GetType().Name, Resource.Id.content_frame);
return true;
}
.
.
.
}
如何在Windows UWP应用程序中实现相同的行为？或者，是否存在用于实现CustomPresenter的Windows MvvmCross应用程序的任何示例？这至少可以让我开始了解如何实施它。
谢谢！
更新：
我终于开始弄清楚如何与客户演示者一起解决这个问题：
public class CustomPresenter : IMvxWindowsViewPresenter
{
IMvxWindowsFrame _rootFrame;
public CustomPresenter(IMvxWindowsFrame rootFrame)
{
_rootFrame = rootFrame;
}
public void AddPresentationHintHandler<THint>(Func<THint, bool> action) where THint : MvxPresentationHint
{
throw new NotImplementedException();
}
public void ChangePresentation(MvxPresentationHint hint)
{
throw new NotImplementedException();
}
public void Show(MvxViewModelRequest request)
{
if (request.ViewModelType == typeof(ShellPageViewModel))
{
//_rootFrame?.Navigate(typeof(ShellPage), null); // throws an exception
((Frame)_rootFrame.UnderlyingControl).Content = new ShellPage();
}
}
}
当我尝试导航到ShellPage时，它失败。因此，当我将Content设置为ShellPage时，它可以工作，但是当我这样做时，ShellPage的ViewModel不会自动初始化。我猜测ViewModels使用OnNavigatedTo在MvvmCross中初始化？
最佳答案
我遇到了同样的问题，并为UWP构建了自定义演示者。它借用了我在某处发现的一个使用片段的Android示例的一些想法。这个想法如下。
我有一个容器视图，其中可以包含带有自己的ViewModels的多个子视图。因此，我希望能够在容器内显示多个视图。
注意：我正在使用MvvmCross 4.0.0-beta3
主持人
using System;
using Cirrious.CrossCore;
using Cirrious.CrossCore.Exceptions;
using Cirrious.MvvmCross.ViewModels;
using Cirrious.MvvmCross.Views;
using Cirrious.MvvmCross.WindowsUWP.Views;
using xxxxx.WinUniversal.Extensions;
namespace xxxxx.WinUniversal.Presenters
{
public class MvxWindowsMultiRegionViewPresenter
: MvxWindowsViewPresenter
{
private readonly IMvxWindowsFrame _rootFrame;
public MvxWindowsMultiRegionViewPresenter(IMvxWindowsFrame rootFrame)
: base(rootFrame)
{
_rootFrame = rootFrame;
}
public override async void Show(MvxViewModelRequest request)
{
var host = _rootFrame.Content as IMvxMultiRegionHost;
var view = CreateView(request);
if (host != null && view.HasRegionAttribute())
{
host.Show(view as MvxWindowsPage);
}
else
{
base.Show(request);
}
}
private static IMvxWindowsView CreateView(MvxViewModelRequest request)
{
var viewFinder = Mvx.Resolve<IMvxViewsContainer>();
var viewType = viewFinder.GetViewType(request.ViewModelType);
if (viewType == null)
throw new MvxException("View Type not found for " + request.ViewModelType);
// Create instance of view
var viewObject = Activator.CreateInstance(viewType);
if (viewObject == null)
throw new MvxException("View not loaded for " + viewType);
var view = viewObject as IMvxWindowsView;
if (view == null)
throw new MvxException("Loaded View is not a IMvxWindowsView " + viewType);
view.ViewModel = LoadViewModel(request);
return view;
}
private static IMvxViewModel LoadViewModel(MvxViewModelRequest request)
{
// Load the viewModel
var viewModelLoader = Mvx.Resolve<IMvxViewModelLoader>();
return viewModelLoader.LoadViewModel(request, null);
}
}
}
IMvxMultiRegionHost
using Cirrious.MvvmCross.ViewModels;
using Cirrious.MvvmCross.WindowsUWP.Views;
namespace xxxxx.WinUniversal.Presenters
{
public interface IMvxMultiRegionHost
{
void Show(MvxWindowsPage view);
void CloseViewModel(IMvxViewModel viewModel);
void CloseAll();
}
}
RegionAttribute
using System;
namespace xxxxx.WinUniversal.Presenters
{
[AttributeUsage(AttributeTargets.Class)]
public sealed class RegionAttribute
: Attribute
{
public RegionAttribute(string regionName)
{
Name = regionName;
}
public string Name { get; private set; }
}
}
这是您需要的三个基础类。接下来，您需要在
IMvxMultiRegionHost派生类中实现MvxWindowsPage。这是我正在使用的：
HomeView.xaml.cs
using System;
using System.Diagnostics;
using System.Linq;
using Windows.Foundation;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Navigation;
using Cirrious.MvvmCross.ViewModels;
using Cirrious.MvvmCross.WindowsUWP.Views;
using xxxxx.Shared.Controls;
using xxxxx.WinUniversal.Extensions;
using xxxxx.WinUniversal.Presenters;
using xxxxx.Core.ViewModels;
namespace xxxxx.WinUniversal.Views
{
public partial class HomeView
: MvxWindowsPage
, IMvxMultiRegionHost
{
public HomeView()
{
InitializeComponent();
}
// ...
public void Show(MvxWindowsPage view)
{
if (!view.HasRegionAttribute())
throw new InvalidOperationException(
"View was expected to have a RegionAttribute, but none was specified.");
var regionName = view.GetRegionName();
RootSplitView.Content = view;
}
public void CloseViewModel(IMvxViewModel viewModel)
{
throw new NotImplementedException();
}
public void CloseAll()
{
throw new NotImplementedException();
}
}
}
完成这项工作的最后一步是在视图中设置实际xaml的方式。您会注意到，我正在使用
SplitView控件，并且正在用ShowView类的HomeView方法中引入的新View替换Content属性。HomeView.xaml
<SplitView x:Name="RootSplitView"
DisplayMode="CompactInline"
IsPaneOpen="false"
CompactPaneLength="48"
OpenPaneLength="200">
<SplitView.Pane>
// Some ListView with menu items.
</SplitView.Pane>
<SplitView.Content>
// Initial content..
</SplitView.Content>
</SplitView>
编辑：
扩展方法
我忘记发布两个扩展方法来确定视图是否声明了
[Region]属性。public static class RegionAttributeExtentionMethods
{
public static bool HasRegionAttribute(this IMvxWindowsView view)
{
var attributes = view
.GetType()
.GetCustomAttributes(typeof(RegionAttribute), true);
return attributes.Any();
}
public static string GetRegionName(this IMvxWindowsView view)
{
var attributes = view
.GetType()
.GetCustomAttributes(typeof(RegionAttribute), true);
if (!attributes.Any())
throw new InvalidOperationException("The IMvxView has no region attribute.");
return ((RegionAttribute)attributes.First()).Name;
}
}
希望这可以帮助。