是否有mvvmcross提供的标签式布局平台？

Question

我正在尝试在xamarin应用程序中添加选项卡式布局。我使用的是mvvmcross平台，但要找到mvvmcross为android和ios提供的标签式布局平台并不容易。如果mvvmcross中有任何平台或示例，请帮助我！谢谢！

Answer 1

TR; DR;

在MvvmCross的文档中，你会在主持人（Xamarin.Android，Xamarin.iOS，Xamarin.Forms）中找到它。

基本上，您必须使用视图属性进行decore以生成选项卡。

很长的例子（这些是使用Mvx 6）

从MvvmCross存储库中的Playground project中提取的示例。

的ViewModels

你将有一个根标签ViewModel，它将成为所有标签的容器，每个标签都有一个ViewModel。

标签根（有两个根提供不同的方法来做同样的事情，并显示一个标签可以导航到另一个，你应该只使用一个）

public class TabsRootViewModel : MvxNavigationViewModel
{
    public TabsRootViewModel(IMvxLogProvider logProvider, IMvxNavigationService navigationService) : base(logProvider, navigationService)
    {
        ShowInitialViewModelsCommand = new MvxAsyncCommand(ShowInitialViewModels);
        ShowTabsRootBCommand = new MvxAsyncCommand(async () => await NavigationService.Navigate<TabsRootBViewModel>());
    }

    public IMvxAsyncCommand ShowInitialViewModelsCommand { get; private set; }

    public IMvxAsyncCommand ShowTabsRootBCommand { get; private set; }

    private async Task ShowInitialViewModels()
    {
        var tasks = new List<Task>();
        tasks.Add(NavigationService.Navigate<Tab1ViewModel, string>("test"));
        tasks.Add(NavigationService.Navigate<Tab2ViewModel>());
        tasks.Add(NavigationService.Navigate<Tab3ViewModel>());
        await Task.WhenAll(tasks);
    }

    private int _itemIndex;

    public int ItemIndex
    {
        get { return _itemIndex; }
        set
        {
            if (_itemIndex == value) return;
            _itemIndex = value;
            Log.Trace("Tab item changed to {0}", _itemIndex.ToString());
            RaisePropertyChanged(() => ItemIndex);
        }
    }
}

public class TabsRootBViewModel : MvxNavigationViewModel
{
    public TabsRootBViewModel(IMvxLogProvider logProvider, IMvxNavigationService navigationService) : base(logProvider, navigationService)
    {
        ShowInitialViewModelsCommand = new MvxAsyncCommand(ShowInitialViewModels);
    }

    public IMvxAsyncCommand ShowInitialViewModelsCommand { get; private set; }

    private async Task ShowInitialViewModels()
    {
        var tasks = new List<Task>();
        tasks.Add(NavigationService.Navigate<Tab1ViewModel, string>("test"));
        tasks.Add(NavigationService.Navigate<Tab2ViewModel>());
        await Task.WhenAll(tasks);
    }

    private int _itemIndex;

    public int ItemIndex
    {
        get { return _itemIndex; }
        set
        {
            if (_itemIndex == value) return;
            _itemIndex = value;
            Log.Trace("Tab item changed to {0}", _itemIndex.ToString());
            RaisePropertyChanged(() => ItemIndex);
        }
    }
}

TAB1

public class Tab1ViewModel : MvxNavigationViewModel<string>
{
    public Tab1ViewModel(IMvxLogProvider logProvider, IMvxNavigationService navigationService) : base(logProvider, navigationService)
    {
        OpenChildCommand = new MvxAsyncCommand(async () => await NavigationService.Navigate<ChildViewModel>());

        OpenModalCommand = new MvxAsyncCommand(async () => await NavigationService.Navigate<ModalViewModel>());

        OpenNavModalCommand = new MvxAsyncCommand(async () => await NavigationService.Navigate<ModalNavViewModel>());

        CloseCommand = new MvxAsyncCommand(async () => await NavigationService.Close(this));

        OpenTab2Command = new MvxAsyncCommand(async () => await NavigationService.ChangePresentation(new MvxPagePresentationHint(typeof(Tab2ViewModel))));
    }

    public override async Task Initialize()
    {
        await Task.Delay(3000);
    }

    string para;
    public override void Prepare(string parameter)
    {
        para = parameter;
    }

    public override void ViewAppeared()
    {
        base.ViewAppeared();
    }

    public IMvxAsyncCommand OpenChildCommand { get; private set; }

    public IMvxAsyncCommand OpenModalCommand { get; private set; }

    public IMvxAsyncCommand OpenNavModalCommand { get; private set; }

    public IMvxAsyncCommand OpenTab2Command { get; private set; }

    public IMvxAsyncCommand CloseCommand { get; private set; }
}

TAB2

public class Tab2ViewModel : MvxNavigationViewModel
{
    public Tab2ViewModel(IMvxLogProvider logProvider, IMvxNavigationService navigationService) : base(logProvider, navigationService)
    {
        ShowRootViewModelCommand = new MvxAsyncCommand(async () => await NavigationService.Navigate<RootViewModel>());

        CloseViewModelCommand = new MvxAsyncCommand(async () => await NavigationService.Close(this));
    }

    public IMvxAsyncCommand ShowRootViewModelCommand { get; private set; }

    public IMvxAsyncCommand CloseViewModelCommand { get; private set; }
}

Xamarin Traditional

Android的

这里的关键是MvxFragmentPresentation属性，它确定它是一个片段，MvxTabLayoutPresentation确定它将被显示为一个标签。显然，标签根目录有一个ViewPager来托管标签页面。

首先，您需要一个视图来托管选项卡（在此示例中，视图也托管在SplitDetailView中，但您可以将它放在任何您想要的位置：

根标签

我假设您希望您的根选项卡是一个片段，您也可以将它作为一个活动（如果您需要，请查看Playground项目）。

[MvxFragmentPresentation(fragmentHostViewType: typeof(SplitDetailView), fragmentContentId: Resource.Id.tabs_frame, addToBackStack: true)]
[Register(nameof(TabsRootBView))]
public class TabsRootBView : MvxFragment<TabsRootBViewModel>
{
    public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        base.OnCreateView(inflater, container, savedInstanceState);

        var view = this.BindingInflate(Resource.Layout.TabsRootBView, null);

        return view;
    }

    public override void OnViewCreated(View view, Bundle savedInstanceState)
    {
        base.OnViewCreated(view, savedInstanceState);

        if (savedInstanceState == null)
        {
            ViewModel.ShowInitialViewModelsCommand.Execute();
        }
    }
}

它的轴：

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:local="http://schemas.android.com/apk/res-auto"
    android:id="@+id/main_content"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <android.support.design.widget.AppBarLayout android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">
        <android.support.v7.widget.Toolbar android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimaryDark"
            local:popupTheme="@style/ThemeOverlay.AppCompat.Light"
            local:layout_scrollFlags="scroll|enterAlways" />
        <android.support.design.widget.TabLayout android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="?attr/colorPrimaryDark"
            android:paddingLeft="16dp"
            local:tabGravity="center"
            local:tabMode="scrollable" />
    </android.support.design.widget.AppBarLayout>
    <android.support.v4.view.ViewPager android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        local:layout_behavior="@string/appbar_scrolling_view_behavior" />
</android.support.design.widget.CoordinatorLayout>

标签1

考虑在根选项卡视图中命名的TabLayoutResourceId和ViewPagerResourceId。

[MvxTabLayoutPresentation(TabLayoutResourceId = Resource.Id.tabs, ViewPagerResourceId = Resource.Id.viewpager, Title = "Tab 1", FragmentHostViewType = typeof(TabsRootBView))]
[Register(nameof(Tab1View))]
public class Tab1View : MvxFragment<Tab1ViewModel>
{
    public override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);

        // Create your fragment here
    }

    public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        base.OnCreateView(inflater, container, savedInstanceState);

        var view = this.BindingInflate(Resource.Layout.Tab1View, null);

        return view;
    }
}

它的轴：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:local="http://schemas.android.com/apk/res-auto"
    android:id="@+id/main_frame"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:text="Show Child"
        local:MvxBind="Click OpenChildCommand;" />
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:text="Show Tab 2"
        local:MvxBind="Click OpenTab2Command;" />
    <FrameLayout
        android:id="@+id/content_frame"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</LinearLayout>

标签2

[MvxTabLayoutPresentation(TabLayoutResourceId = Resource.Id.tabs, ViewPagerResourceId = Resource.Id.viewpager, Title = "Tab 2", FragmentHostViewType = typeof(TabsRootBView))]
[Register(nameof(Tab2View))]
public class Tab2View : MvxFragment<Tab2ViewModel>
{
    public override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);

        // Create your fragment here
    }

    public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        base.OnCreateView(inflater, container, savedInstanceState);

        var view = this.BindingInflate(Resource.Layout.Tab2View, null);

        return view;
    }
}

它的轴：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:local="http://schemas.android.com/apk/res-auto"
    android:id="@+id/main_frame"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <Button android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:text="Close tab"
        local:MvxBind="Click CloseViewModelCommand;" />
</LinearLayout>

iOS版

这里的关键是MvxRootPresentation属性，它确定它是根并且给它是一个MvxTabBarViewController它将托管标签。除此之外，MvxTabPresentation确定ViewController是一个标签。

根标签

[MvxFromStoryboard("Main")]
[MvxRootPresentation(WrapInNavigationController = true)]
public partial class TabsRootView : MvxTabBarViewController<TabsRootViewModel>
{
    private bool _isPresentedFirstTime = true;

    public TabsRootView(IntPtr handle) : base(handle)
    {
    }

    public override void ViewWillAppear(bool animated)
    {
        base.ViewWillAppear(animated);

        if (ViewModel != null && _isPresentedFirstTime)
        {
            _isPresentedFirstTime = false;
            ViewModel.ShowInitialViewModelsCommand.ExecuteAsync(null);
        }
    }

    protected override void SetTitleAndTabBarItem(UIViewController viewController, MvxTabPresentationAttribute attribute)
    {
        // you can override this method to set title or iconName
        if (string.IsNullOrEmpty(attribute.TabName))
            attribute.TabName = "Tab 2";
        if (string.IsNullOrEmpty(attribute.TabIconName))
            attribute.TabIconName = "ic_tabbar_menu";

        base.SetTitleAndTabBarItem(viewController, attribute);
    }

    public override bool ShowChildView(UIViewController viewController)
    {
        var type = viewController.GetType();

        return type == typeof(ChildView)
            ? false
            : base.ShowChildView(viewController);
    }

    public override bool CloseChildViewModel(IMvxViewModel viewModel)
    {
        var type = viewModel.GetType();

        return type == typeof(ChildViewModel)
            ? false
            : base.CloseChildViewModel(viewModel);
    }
}

标签1

[MvxFromStoryboard("Main")]
[MvxTabPresentation(WrapInNavigationController = true, TabIconName = "home", TabName = "Tab 1")]
public partial class Tab1View : MvxViewController<Tab1ViewModel>
{
    public Tab1View(IntPtr handle) : base(handle)
    {
    }

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

        var set = this.CreateBindingSet<Tab1View, Tab1ViewModel>();

        set.Bind(btnModal).To(vm => vm.OpenModalCommand);
        set.Bind(btnNavModal).To(vm => vm.OpenNavModalCommand);
        set.Bind(btnChild).To(vm => vm.OpenChildCommand);
        set.Bind(btnTab2).To(vm => vm.OpenTab2Command);

        set.Apply();
    }
}

标签2

[MvxFromStoryboard("Main")]
[MvxTabPresentation]
public partial class Tab2View : MvxViewController<Tab2ViewModel>
{
    public Tab2View(IntPtr handle) : base(handle)
    {
    }

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

        var set = this.CreateBindingSet<Tab2View, Tab2ViewModel>();

        set.Bind(btnShowStack).To(vm => vm.ShowRootViewModelCommand);
        set.Bind(btnClose).To(vm => vm.CloseViewModelCommand);

        set.Apply();
    }
}

Xamarin表格

根标签

这里的主要内容是views:MvxTabbedPage和MvxTabbedPagePresentation，表明它将是一个主页标签的页面。

<?xml version="1.0" encoding="UTF-8"?>
<views:MvxTabbedPage x:TypeArguments="viewModels:TabsRootViewModel"
    xmlns="http://xamarin.com/schemas/2014/forms" 
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
    xmlns:views="clr-namespace:MvvmCross.Forms.Views;assembly=MvvmCross.Forms"
    xmlns:mvx="clr-namespace:MvvmCross.Forms.Bindings;assembly=MvvmCross.Forms"
    xmlns:viewModels="clr-namespace:Playground.Core.ViewModels;assembly=Playground.Core"
    x:Class="Playground.Forms.UI.Pages.TabsRootPage" Title="TabsRoot page">
    <ContentPage.Content>

    </ContentPage.Content>
</views:MvxTabbedPage>

[MvxTabbedPagePresentation(TabbedPosition.Root, NoHistory = true)]
public partial class TabsRootPage : MvxTabbedPage<TabsRootViewModel>
{
    public TabsRootPage()
    {
        InitializeComponent();
    }

    private bool _firstTime = true;

    protected override void OnAppearing()
    {
        base.OnAppearing();
        if (_firstTime)
        {
            //ViewModel.ShowInitialViewModelsCommand.Execute();
            ViewModel.ShowInitialViewModelsCommand.ExecuteAsync(null);
            _firstTime = false;
        }
    }

    protected override void OnViewModelSet()
    {
        base.OnViewModelSet();
    }
}

标签1

这里的主要内容是MvxTabbedPagePresentation，表明它将是一个标签。

<?xml version="1.0" encoding="UTF-8"?>
<views:MvxContentPage x:TypeArguments="viewModels:Tab1ViewModel"
    xmlns="http://xamarin.com/schemas/2014/forms" 
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
    xmlns:views="clr-namespace:MvvmCross.Forms.Views;assembly=MvvmCross.Forms"
    xmlns:mvx="clr-namespace:MvvmCross.Forms.Bindings;assembly=MvvmCross.Forms"
    xmlns:viewModels="clr-namespace:Playground.Core.ViewModels;assembly=Playground.Core"
    x:Class="Playground.Forms.UI.Pages.Tab1Page" Title="Tab1 page">
    <ContentPage.Content>
      <StackLayout Margin="10">
            <Label Text="I'm a tab page" />
            <Button Text="Show Child" mvx:Bi.nd="Command OpenChildCommand"/>
            <Button Text="Show Modal" mvx:Bi.nd="Command OpenModalCommand"/>
        </StackLayout>
    </ContentPage.Content>
</views:MvxContentPage>

[MvxTabbedPagePresentation(WrapInNavigationPage = false, Title = "Tab1")]
public partial class Tab1Page : MvxContentPage<Tab1ViewModel>
{
    public Tab1Page()
    {
        InitializeComponent();
    }
}

标签2

<?xml version="1.0" encoding="UTF-8"?>
<views:MvxContentPage x:TypeArguments="viewModels:Tab2ViewModel"
    xmlns="http://xamarin.com/schemas/2014/forms" 
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
    xmlns:views="clr-namespace:MvvmCross.Forms.Views;assembly=MvvmCross.Forms"
    xmlns:mvx="clr-namespace:MvvmCross.Forms.Bindings;assembly=MvvmCross.Forms"
    xmlns:viewModels="clr-namespace:Playground.Core.ViewModels;assembly=Playground.Core"
    x:Class="Playground.Forms.UI.Pages.Tab2Page" Title="Tab2 page">
    <ContentPage.Content>
      <StackLayout Margin="10">
            <Label Text="I'm a tab page" />
            <Button Text="Close tab" mvx:Bi.nd="Command CloseViewModelCommand"/>
        </StackLayout>
    </ContentPage.Content>
</views:MvxContentPage>

[MvxTabbedPagePresentation(WrapInNavigationPage = false)]
public partial class Tab2Page : MvxContentPage<Tab2ViewModel>
{
    public Tab2Page()
    {
        InitializeComponent();
    }
}

也许这个例子不够饱满，所以你可以查看Playground project的MvvmCross repository，看看它是否完整。

HIH