如何在所有页面的导航栏中添加图标？

所以我正在尝试在我的NavigationBar中实现一个图标，以便在我的所有页面中都可以看到它...我正在使用xamarin表单，因此我希望它能够在android和iOS中都能够使用...我不是确定如何执行此操作，但是我试图将其添加到MyCar.xaml中

<customControls:BasePage xmlns="http://xamarin.com/schemas/2014/forms"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
    xmlns:android="clr-namespace:Xamarin.Forms.PlatformConfiguration.AndroidSpecific;assembly=Xamarin.Forms.Core"
    xmlns:views="clr-namespace:OficinaDigitalX.Views"   
    xmlns:customControls="clr-namespace:OficinaDigitalX.ViewModel"
    x:Name="MyCar">
<customControls:BasePage.Content>
    <AbsoluteLayout>



        <StackLayout Padding="10, 0, 10, 0">


            <ListView 
                ItemsSource="{Binding Path=CarList}"
                IsPullToRefreshEnabled="False"
                SelectedItem="{Binding Path=SelectedCar}">
                <ListView.Header>
                    <Label Text="Os Meus Carros" FontSize="Large" />
                </ListView.Header>
                <ListView.ItemTemplate>
                    <DataTemplate>
                        <TextCell Text="{Binding VID}" 
                                  TextColor="Black" 
                                  Detail="{Binding LicensePlate}"/>
                    </DataTemplate>
                </ListView.ItemTemplate>
            </ListView>
        </StackLayout>
    </AbsoluteLayout>
</customControls:BasePage.Content>
</customControls:BasePage>  

这是我的MyCar.xaml.cs

namespace OficinaDigitalX.Views
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class MyCar : ViewModel.BasePage
{

    public MyCar()
    {
        Extensions.LoadFromXaml(this, typeof(MyCar));
        BindingContext = new MyCarViewModel(Navigation);

    }

这是我的MyCarViewModel.cs

public class MyCarViewModel : ViewModelBase
{
    public MyCarViewModel()
    {
    }
    public MyCarViewModel(INavigation navigation)
    {
        this.Navigation = navigation;
        this.SelectedCar = null;
        GetClientCars();
    }

    private List<CarInfo> _CarList;

    public List<CarInfo> CarList
    {
        get
        {
            return _CarList;
        }

        set
        {
            _CarList = value;
            OnPropertyChanged("CarList");
        }
    }

    private CarInfo _SelectedCar;

    public CarInfo SelectedCar
    {
        get
        {
            return _SelectedCar;
        }

        set
        {
            _SelectedCar = value;
            OnPropertyChanged("SelectedCar");

            if (_SelectedCar != null)
                ChangeWindow(_SelectedCar);
        }
    }

    public INavigation Navigation { get; set; }

    private void ChangeWindow(CarInfo car)
    {

        Navigation.PushAsync(new Interactions(car));
        this.SelectedCar = null;

    }

    public void GetClientCars()
    {
        string command = "asdasd";
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(string.Format(MainPage.server + command));
        request.ContentType = "application/json";
        request.Method = "POST";
        //request.ContentLength = 999999;

        using (var stream = new StreamWriter(request.GetRequestStream()))
        {
            string postData = JsonConvert.SerializeObject(command);

            //stream.Write(postData);
            stream.Flush();
            stream.Close();
        }

        HttpWebResponse response = null;

        try
        {
            response = (HttpWebResponse)request.GetResponse();
            using (var responseString = new StreamReader(response.GetResponseStream()))
            {
                CarList = JsonConvert.DeserializeObject<List<CarInfo>>(responseString.ReadToEnd());
            }
        }
        catch (WebException ex)
        {
            using (StreamReader reader = new StreamReader(ex.Response.GetResponseStream()))
            {

            }
            throw;
        }
    }

}
}

有人能帮忙吗？