Xamarin

sql.cs

using System;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Windows.Input;
using Xamarin.Forms;

namespace FiapCoin.ViewModel
{
    public class LoginViewModel : INotifyPropertyChanged
    {
        public ICommand BotaoEntrarCommand { get; set; }
        public ICommand BotaoSairCommand { get; set; }

        private void executedMethod()
        {
            App.Current.MainPage.DisplayAlert("Só", "Salve", "pra geral");
            MessagingCenter.Send<String>("", "LoginSucesso");
        }
        public LoginViewModel()
        {
            BotaoEntrarCommand = new Command(()=>
            {
                App.Current.MainPage.DisplayAlert("Fabrica de bico", "arsenal de fuzil", "novo");
                MessagingCenter.Send<String>("", "LoginSucesso");
            });

            BotaoSairCommand = new Command(() =>
            {
                App.Current.MainPage.DisplayAlert("Quero do boldo", "entre rajadas e pipocos", "manda buscar");
                MessagingCenter.Send<String>("", "Sair");
            });
        }

        public event PropertyChangedEventHandler PropertyChanged;
        protected virtual void NotifyPropertyChanged([CallerMemberName] string propertyName = "")
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }

        private string usuario;
        public string Usuario
        {
            get { return usuario; }
            set
            {
                if (usuario != value)
                {
                    usuario = value;
                    NotifyPropertyChanged();
                }
            }
        }

        private string senha;
        public string Senha
        {
            get
            {
                return senha;
            }
            set
            {
                if (senha != value)
                {
                    senha = value;
                    NotifyPropertyChanged();
                }
            }
        }
    }
}