BindingContext ViewModel Sample

Servico.cs

namespace DocHouse.Models.Entities
{
    public class Servico
    {
        public int Id { get; set; }
        public string NomeServico { get; set; }
        public string Imagem { get; set; }
        public double Valor { get; set; }
    }
}

Servicos.xaml

<StackLayout>
        <ActivityIndicator IsRunning="{Binding IsBusy}" IsVisible="{Binding IsBusy}"/>

        <Label Text="Carregando..." IsVisible="{Binding IsBusy}" HorizontalOptions="Center" TextColor="White"/>
        <controls:FlowListView 
        HorizontalOptions="CenterAndExpand"
        x:Name="flowListView" 
        FlowColumnCount="2" 
        RowHeight="150"
        FlowUseAbsoluteLayoutInternally="False" 
        FlowColumnExpand="None"
        FlowItemTappedCommand="{Binding ServicoCommand}"
        FlowItemsSource="{Binding ListaServicos}" >
            <controls:FlowListView.FlowColumnTemplate>
                <DataTemplate>
                    <StackLayout
                    Padding="10"
                    HorizontalOptions="CenterAndExpand"
                    VerticalOptions="CenterAndExpand">
                        <Image 
                        HeightRequest="100"
                        WidthRequest="100"
                           Source="{Binding Imagem}"></Image>
                        <Label 
                           FontSize="Medium"
                           TextColor="Black"
                           HorizontalTextAlignment="Center"
                           Text="{Binding NomeServico}"/>
                    </StackLayout>
                </DataTemplate>
            </controls:FlowListView.FlowColumnTemplate>
        </controls:FlowListView>
    </StackLayout>

Servicos.xaml.cs

namespace DocHouse.Views.Consulta
{
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class Consulta1Servicos : ContentPage
    {
    private readonly ServicosViewModel _servicosVm;
        public Consulta1Servicos()
        {
            InitializeComponent();
            _servicosVm = this.BindingContext = new ServicosViewModel();
        }
    }
}

ServicosViewModel.cs

namespace DocHouse.ViewModels.Consulta
{
    public class Consulta1ServicosViewModel : BaseViewModel
    {
        public DelegateCommand<Servico> ServicoCommand { get; set; }
        private readonly INavigationService _navigationService;
        private readonly IPageDialogService _dialogService;
        private readonly RestConsulta _restConsulta;

        private List<Servico> _listaServicos;
        public List<Servico> ListaServicos
        {
            get => _listaServicos;
            set => SetProperty(ref _listaServicos, value);
        }

        private bool _isBusy;
        public bool IsBusy
        {
            get { return _isBusy; }
            set { SetProperty(ref _isBusy, value); }
        }

        public Consulta1ServicosViewModel(INavigationService navigationService, IPageDialogService dialogService)
        {
            _navigationService = navigationService;
            _dialogService = dialogService;
            ServicoCommand = new DelegateCommand<Servico>(ExecuteServicoCommand);
            ListaServicos = new List<Servico>();
            _restConsulta = new RestConsulta();
            Dados();
        }

        private async void ExecuteServicoCommand(Servico obj)
        {
            var p = new NavigationParameters { { "servico", obj } };
            await _navigationService.NavigateAsync("Consulta2Prestadores", p);
        }

        private async void Dados()
        {
            try
            {
                IsBusy = true;
                var list = await _restConsulta.GetServices();
                ListaServicos = list;
            }
            catch (System.Exception ex)
            {
                Debug.WriteLine(ex.Message);
                IsBusy = false;
                throw;
            }
            finally
            {
                IsBusy = false;   
            }
        }
    }
}