XamarinFormsEventAggregator

MainPage.xaml

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="XamarinFormsEventAggregatorSample.MainPage">

    <StackLayout>
        <Frame BackgroundColor="#2196F3" Padding="24" CornerRadius="0">
            <Label Text="EventAggregator" HorizontalTextAlignment="Center" TextColor="White" FontSize="36"/>
        </Frame>
        <Label Text="Write a message on the other screen and go back" FontSize="Title" Padding="{StaticResource SamplePadding}"/>
        <Label Text="{Binding Text}" FontSize="16" Padding="{StaticResource SamplePadding}"/>
        <Button Text="let's write a message" Command="{Binding TextViewCommand}"></Button>
      
    </StackLayout>

</ContentPage>