Updating content between tabs binded by Preference - xamarin.forms

Question

I am using a tabbed app and I have a button on one tab, when the user clicks then it increments a Preference and I want to update its value on another tab that is Binded to a label. I tried to experiment with MVVM but I couldnt figure it out.
Page 1 view:
public partial class Page1View: ContentPage
{
public Page1View()
{
InitializeComponent();
}
private void Button_Clicked(object sender, EventArgs e)
{
Preferences.Set("Total", Preferences.Get("Total", 0)+1);
}
}
Page 2 Viewmodule:
public class Page2ViewModule : INotifyPropertyChanged
{
public int Total
{
get => Preferences.Get(nameof(Total), 0);
set
{
if (Preferences.Get(nameof(Total),0) == value)
return;
Preferences.Set(nameof(Total), value);
OnPropertyChanged(nameof(Total));
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
var changed = PropertyChanged;
if (changed != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
Here's what I done with MessagingCenter. On the button click event I sent a message like this:
private void Button_Clicked(object sender, EventArgs e)
{
Preferences.Set("Total", Preferences.Get("Total", 0)+1);
MessagingCenter.Send<Page>(this, "test");
}
In the Page2 view module I added a constructor that subscribes to message:
public Page2ViewModule()
{
MessagingCenter.Subscribe<Page>(this, "test", (p) =>
{
Total = Preferences.Get(nameof(Total), 0);
});
}
And that still doesn't work. But I'm not sure would this be the best way to do it? Or is there a more efficient way?

Answer 1

For Jason's question: Page2 already been created and the Subscribe method execute before you call Send, I test at my side, Page2 is been created and the Subscribe method execute after you call Send, so I think it works fine using MessagingCenter to notify each page when the Preference has been updated.
Tab one Page.
private void btn1_Clicked(object sender, EventArgs e)
{
Preferences.Set("Total", Preferences.Get("Total", 0) + 1);
label1.Text = Preferences.Get("Total", 0).ToString();
MessagingCenter.Send<Page>(this, "test");
}
Tab two page.
<ContentPage.Content>
<StackLayout>
<Label Text="{Binding Total}" />
</StackLayout>
</ContentPage.Content>
public partial class Tab2 : ContentPage
{
public Tab2()
{
InitializeComponent();
this.BindingContext = new Page2ViewModule();
}
}
public class Page2ViewModule : ViewModelBase
{
private int _Total;
public int Total
{
get { return _Total; }
set
{
_Total = value;
RaisePropertyChanged("Total");
}
}
public Page2ViewModule()
{
MessagingCenter.Subscribe<Page>(this, "test", (p) =>
{
Total = Preferences.Get("Total", 0);
});
}
}