MVVM Example 3 A new Approach to property Changed

MainPage.Xaml will look Like this:

	<?xml version="1.0" encoding="utf-8" ?>
	<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
	xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
	xmlns:local="clr-namespace:MvvmExample3"
	x:Class="MvvmExample3.MainPage">
	<ContentPage.Padding>
	<OnPlatform x:TypeArguments="Thickness"
	iOS="20, 40, 20, 20"
	Android="20, 20, 20, 20"
	WinPhone="20, 20, 20, 20" />
	</ContentPage.Padding>
	<ContentPage.Content>
	<StackLayout VerticalOptions="FillAndExpand"
	HorizontalOptions="FillAndExpand"
	Orientation="Vertical"
	Spacing="15">
	<Label Text="PersonName"/>
	<Entry Text="{Binding PersonName}" Placeholder="Full Name"/>
	<Label Text="WorksIn"/>
	<Entry Text="{Binding WorksIn}" Placeholder="Your Website"/>
	<StackLayout Orientation="Horizontal" Spacing="10">
	<Label Text="Save Data?"/>
	<Switch IsToggled="{Binding MySwitch}"/>
	</StackLayout>
	<Label Text="{Binding DisplayMessage}"/>
	</StackLayout>
	</ContentPage.Content>
	</ContentPage>

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MainPage.Xaml.cs will look Like this:

	using System;
	using System.Collections.Generic;
	using System.Linq;
	using System.Text;
	using System.Threading.Tasks;
	using Xamarin.Forms;
	namespace MvvmExample3
	{
	public partial class MainPage : ContentPage
	{
	public MainPage()
	{
	InitializeComponent();
	BindingContext = new ViewModel.MyNewViewModel();
	}
	}
	}

view raw MainPage.xaml.cs hosted with ❤ by GitHub

MyNewViewModel.cs will look Like this:

	using System;
	using System.Collections.Generic;
	using System.ComponentModel;
	using System.Runtime.CompilerServices;
	using System.Text;
	namespace MvvmExample3.ViewModel
	{
	public class MyNewViewModel : INotifyPropertyChanged
	{
	string firstname = "Samir";
	string lastname = "Xamarin University";
	bool myswitch;
	public event PropertyChangedEventHandler PropertyChanged;
	void OnPropertyChanged([CallerMemberName] string name = "")
	{
	PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
	}
	public bool MySwitch
	{
	get { return myswitch; }
	set
	{
	myswitch = value;
	OnPropertyChanged();
	OnPropertyChanged(nameof(DisplayMessage));
	}
	}
	public string PersonName
	{
	get { return firstname; }
	set
	{
	firstname = value;
	OnPropertyChanged();
	OnPropertyChanged(nameof(DisplayMessage));
	}
	}
	public string WorksIn
	{
	get { return lastname; }
	set
	{
	lastname = value;
	OnPropertyChanged();
	OnPropertyChanged(nameof(DisplayMessage));
	}
	}
	public string DisplayMessage
	{
	get
	{
	return $"Mr {PersonName}" + $"Worksin"
	+ $"{WorksIn}"
	+ $"{(myswitch ? "saved to database" : " is not saved to database")}";
	}
	}
	}
	}

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