1. 安装nuget
Xamarin.Forms
XLabs.Forms

2. MainActivity.cs  (Android)

public class MainActivity : XFormsApplicationDroid
    {
        /// <summary>
        /// Called when [create].
        /// </summary>
        /// <param name="bundle">The bundle.</param>
        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);
            if (!Resolver.IsSet)
            {
                this.SetIoc();
            }
            else
            {
                var app = Resolver.Resolve<IXFormsApp>() as IXFormsApp<XFormsApplicationDroid>;
                if (app != null) app.AppContext = this;
            }


            Xamarin.Forms.Forms.Init(this, bundle);
            this.LoadApplication(new App());
        }


        /// <summary>
        /// Sets the IoC.
        /// </summary>
        private void SetIoc()
        {
            var resolverContainer = new SimpleContainer();


            var app = new XFormsAppDroid();
            app.Init(this);


            resolverContainer.Register<IDevice>(t => AndroidDevice.CurrentDevice)
                .Register<IMediaPicker, MediaPicker>();


            Resolver.SetResolver(resolverContainer.GetResolver());
        }
    

3. ViewModel (Portable)

CamaraViewModel.cs

4. View (portable)

Photo.xaml

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http:///schemas/2014/forms"
             xmlns:x="http:///winfx/2009/xaml"
             xmlns:viewModels="clr-namespace:PhotoSample.ViewModels;assembly=PhotoSample"
             x:Class="PhotoSample.Views.Photo">


  <ContentPage.BindingContext>
    <viewModels:CameraViewModel />
  </ContentPage.BindingContext>


  <StackLayout>
    <Button Text="Take Picture" Command="{Binding TakePictureCommand}" />
    <Button Text="Select Image from Picture Library" Command="{Binding SelectPictureCommand}" />
    <Button Text="Select Video from Picture Library " Command="{Binding SelectVideoCommand}" />
    <Image Source="{Binding ImageSource}" VerticalOptions="CenterAndExpand" />
    <Entry Text="{Binding VideoInfo}" VerticalOptions="CenterAndExpand" />
  </StackLayout>


</ContentPage>

在App.cs （portable） 初始view指向photo即可

MainPage = new Photo();