<StackLayout
            Margin="20"
            Orientation="Horizontal" 
            VerticalOptions="Start">
            <Label Text="Mobile"
                    VerticalOptions="Center" />
            <CheckBox IsChecked="true" 				  
                        CheckedChanged="OnCheckedChanged" />
        </StackLayout>
                

        void OnCheckedChanged(object sender, CheckedChangedEventArgs e)
        {
            Console.WriteLine("OnCheckedChanged");
        }