Creating the XAML file

Xamarin.Forms provides us with some navigation modes including Hierarchical Navigation, Tabbedpage, MasterDetailPage and Modal Pages, etc. For our requirements, we want to have a hamburger menu on the main page. So we can use MasterDetailPage, which is a root page of the application and contains two areas: the left one is the MasterPage, the right one is the DetailPage. We can place the menu in the MasterPage. When clicking the menu item, the navigation service will show another page in DetailPage area.

In MvvmCross, there are some corresponding MvxFromsPagePresenter for different page types in Xamarin.Forms, which define how a view will be displayed. We use MvxPagePresentationAttribute to specify different page types. For more details, please view the documentation here: Xamarin.Forms View Presenter.

Open the App.cs file in the MvxFormsMasterDetailDemo.Core project. Notice that the framework will start HomeViewModel as the first page. Now let us create a MasterDetailPage and use it to replace the first page.

Right click the Pages folder in the MvxFormsMasterDetailDemo.UI project and select Add-New Item. Select Content Page from Xamarin.Forms category, like this:

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Open the MasterDetailPage.xaml file. Notice that this page is a ContentPage. We need to change it to inherit from MvxMasterDetailPage. Replace the XAML code with the following code:

<?xml version="1.0" encoding="utf-8" ?>
<views:MvxMasterDetailPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="MvxFormsMasterDetailDemo.UI.Pages.MasterDetailPage"
xmlns:views="clr-namespace:MvvmCross.Forms.Views;assembly=MvvmCross.Forms"
xmlns:viewModels="clr-namespace:MvxFormsMasterDetailDemo.Core.ViewModels;assembly=MvxFormsMasterDetailDemo.Core"
x:TypeArguments="viewModels:MasterDetailViewModel">
</views:MvxMasterDetailPage>

We use MvxMasterDetailPage to replace the default ContentPage type. To do this, we need to add this code:

xmlns:views="clr-namespace:MvvmCross.Forms.Views;assembly=MvvmCross.Forms"

To set the ViewModel of the MasterDetailPage, we need to specify the x:TypeArguments with the value viewModels:MasterDetailViewModel. Do not forget to import the viewModels namespace by adding xmlns:viewModels="clr-namespace:MvxFormsMasterDetailDemo.Core.ViewModels;assembly=MvxFormsMasterDetailDemo.Core".

Open the MasterDetailPage.xaml.cs file, replace the base class of it from ContentPage to MvxMasterDetailPage<MasterDetailViewModel>. Add the MvxMasterDetailPagePresentation attribute to the class, as the following code:

using MvvmCross.Forms.Presenters.Attributes;
using MvvmCross.Forms.Views;
using MvxFormsMasterDetailDemo.Core.ViewModels;
using Xamarin.Forms.Xaml;
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namespace MvxFormsMasterDetailDemo.UI.Pages
{
[XamlCompilation(XamlCompilationOptions.Compile)]
[MvxMasterDetailPagePresentation(Position = MasterDetailPosition.Root, WrapInNavigationPage = false, Title = "MasterDetail Page")]
public partial class MasterDetailPage : MvxMasterDetailPage<MasterDetailViewModel>
{
public MasterDetailPage()
{
InitializeComponent();
}
}
}

Let's take a look at the MvxMasterDetailPagePresentation attribute. There are some very important properties of MvxMasterDetailPagePresentation. Position is an enum value that is used to indicate the type of the page, which is Root here. Please set the other properties as shown, otherwise, you might get some odd results.