在 xamarin-forms 的 xaml 内容页面中嵌入和数据绑定 android spinner

Question

I am trying to embed a native android spinner in a xamarin forms content page. I have had some joy embedding a check-box from the developer documentation but I want to add a spinner. From the documentation, I should be able to data-bind normally to any native control. So I data-bound an ObservableCollection of strings to a native spinner like so:

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
         xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
         xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms"
         prism:ViewModelLocator.AutowireViewModel="True"
         xmlns:android="clr-
namespace:Android.Widget;assembly=Mono.Android;targetPlatform=Android"
         xmlns:androidForms="clr-namespace:Xamarin.Forms;
assembly=Xamarin.Forms.Platform.Android;targetPlatform=Android"
         x:Class="CashFlowBuddie.Views.SelectPage"
         Title="{Binding Title}">
<ContentView HorizontalOptions="CenterAndExpand" VerticalOptions="CenterAndExpand">
    <Label Text="Hi there from new app" FontSize="Large" FontAttributes="Bold" TextColor="Aquamarine"/>
    <android:Spinner x:Arguments="{x:Static androidForms:Forms.Context}" ItemsSource="{Binding TextNames}" />
</ContentView>
</ContentPage>

This is my xaml page's viewmodel:

public class SelectPageViewModel : ViewModelBase
{
    private ObservableCollection<string> _text;
    public ObservableCollection<string> TextNames
    {
        get { return _text; }
        set { SetProperty(ref _text, value); }
    }
    public SelectPageViewModel(INavigationService navigationService, IPageDialogService dialogService):base(navigationService,dialogService)
    {
        Title = "Select Option Page";
        TextNames = new ObservableCollection<string>
        {
            "First",
            "Second",
            "Third"
        };
    }
}

From this you can tell that its a prism powered xamarin forms app. And I register my page for navigation properly:

public partial class App : PrismApplication
{
    public App(IPlatformInitializer initializer = null) : base(initializer) { }

    protected override void OnInitialized()
    {
        InitializeComponent();

        NavigationService.NavigateAsync("NavigationPage/MainPage/SelectPage");
    }

    protected override void RegisterTypes()
    {
        Container.RegisterTypeForNavigation<MainPage>();
        Container.RegisterTypeForNavigation<MainNavigation>("NavigationPage");
        Container.RegisterTypeForNavigation<SelectPage>();
    }
}

I made sure that I disabled XamlC from AssemblyInfo.cs since I cannot use XamlC when embedding native controls and views. My app crashes when I do the data-binding to the observablecollection of textnames. So I would like to know if someone has done this and had any joy? I looked at the spinner in the xamarin.android docs says a xml backed string array is created and is the source of data for the spinner. I did something similar using an observablecollection but if I run the app it just crashes. If I run the app without the data binding, it works and shows the app with the spinner but no data.

Can anyone shed any light on how to get this done? looked at docs and nothing so far though I am still digging?

Thanks

Answer 1

You may refer to Subclassing Native Views , seems like for control like Spinner is not suitable for instantiating in XAML. The ItemsSource property should be created in the subclass of native Spinner

To check the official demo, you may refer to Subclassed Native Views .