public class MyViewModel: INotifyPropertyChanged { public ICommand TestCommmand => new Command(TestMethod); private void TestMethod(object obj) { NotificationsNumber = 168; } private int _notificationsNumber = 0; public int NotificationsNumber { get => _notificationsNumber; set => SetProperty(ref _notificationsNumber, value); } public MyViewModel() { NotificationsNumber = 0; } bool SetProperty<T>(ref T storage, T value, [CallerMemberName] string propertyName = null) { if (Object.Equals(storage, value)) return false; storage = value; OnPropertyChanged(propertyName); return true; } protected void OnPropertyChanged([CallerMemberName] string propertyName = null) { PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName)); } public event PropertyChangedEventHandler PropertyChanged; } 

 <?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:xct="http://xamarin.com/schemas/2020/toolkit" xmlns:formapp826="clr-namespace:FormApp826" x:Class="FormApp826.MainPage"> <ContentPage.BindingContext> <formapp826:MyViewModel></formapp826:MyViewModel> </ContentPage.BindingContext> <StackLayout Padding="10"> <Label Text="{Binding NotificationsNumber}" HorizontalOptions="Center" FontSize="Header" /> <xct:BadgeView Margin="10" BackgroundColor="Red" FontAttributes="Bold" FontSize="Medium" TextColor="White" Text="{Binding NotificationsNumber}"> <Label Text="This label has a badge in the top-right"/> </xct:BadgeView> <Button Text="change value" Command="{Binding TestCommmand}" /> </StackLayout> </ContentPage>