azimuthdeveloper

    public class AboutViewModel : BaseViewModel
    {
        public AboutViewModel()
        {
            Title = "About";
            OpenWebCommand = new Command(async () => await Browser.OpenAsync("https://aka.ms/xamarin-quickstart"));
        }

        public ICommand OpenWebCommand { get; }
    }

azimuthdeveloper

                <Button Margin="0,10,0,0" Text="Learn more"
                        Command="{Binding OpenWebCommand}"
                        BackgroundColor="{StaticResource Primary}"
                        TextColor="White" />

azimuthdeveloper

    <Shell.Resources>
        <ResourceDictionary>
            <Style x:Key="BaseStyle" TargetType="Element">
                <Setter Property="Shell.BackgroundColor" Value="{StaticResource Primary}" />
                <Setter Property="Shell.ForegroundColor" Value="White" />
                <Setter Property="Shell.TitleColor" Value="White" />
                <Setter Property="Shell.DisabledColor" Value="#B4FFFFFF" />
                <Setter Property="Shell.UnselectedColor" Value="#95FFFFFF" />
                <Setter Property="Shell.TabBarBackgroundColor" Value="{StaticResource Primary}" />
                <Setter Property="Shell.TabBarForegroundColor" Value="White"/>

azimuthdeveloper

<?xml version="1.0" encoding="utf-8" ?>
<Application xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="App1.App">
    <!--
        Define global resources and styles here, that apply to all pages in your app.
    -->
    <Application.Resources>
        <ResourceDictionary>
            <Color x:Key="Primary">#2196F3</Color>

azimuthdeveloper

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {

azimuthdeveloper

  floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.

azimuthdeveloper

        private async void OnSave()
        {
            Item newItem = new Item()
            {
                Id = Guid.NewGuid().ToString(),
                Text = Text,
                Description = Description
            };

            await DataStore.AddItemAsync(newItem);

azimuthdeveloper

        public NewItemViewModel()
        {
            SaveCommand = new Command(OnSave, ValidateSave);
            CancelCommand = new Command(OnCancel);
            this.PropertyChanged +=
                (_, __) => SaveCommand.ChangeCanExecute();
        }

azimuthdeveloper

        public Command SaveCommand { get; }
        public Command CancelCommand { get; }

azimuthdeveloper

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Input;
using testxamarin.Models;
using Xamarin.Forms;

namespace testxamarin.ViewModels
{
    public class NewItemViewModel : BaseViewModel