Fix LocalizedString gets unsubscribed while still in use (#987)

* Fixed all the things

* Make PersistentObservableObject abstract

* Reverse the inheritance

* Commit to rerun tests

* Remove PersistentObservableObject

* Grammar

Author: maxkoshevoi

src/CommunityToolkit/Xamarin.CommunityToolkit.UnitTests/Helpers/LocalizedStringTests/LocalizedStringTests.cs

@@ -61,6 +61,23 @@ public void LocalizedStringTests_ImplicitConversion_ValidImplementation()
 			Assert.NotNull(localizedString);
 		}
 
+		[Fact]
+		public void LocalizedStringTests_WeekSubscribe_ValidImplementation()
+		{
+			// Arrange
+			var isTrigered = false;
+			var culture2 = new CultureInfo("en");
+			localizedString = new LocalizedString(localizationManager, () => string.Empty);
+			localizedString.PropertyChanged += (_, __) => isTrigered = true;
+
+			// Act
+			GC.Collect();
+			localizationManager.CurrentCulture = culture2;
+
+			// Assert
+			Assert.True(isTrigered);
+		}
+
 		[Fact]
 		public void LocalizedStringTests_Disposed_IfNoReferences()
 		{

src/CommunityToolkit/Xamarin.CommunityToolkit/Helpers/LocalizationResourceManager.shared.cs

@@ -29,7 +29,7 @@ public void Init(ResourceManager resource) =>
 		public void Init(ResourceManager resource, CultureInfo initialCulture)
 		{
 			resourceManager = resource;
-			SetCulture(initialCulture);
+			CurrentCulture = initialCulture;
 		}
 
 		public string GetValue(string text) =>

src/CommunityToolkit/Xamarin.CommunityToolkit/Helpers/LocalizedString.shared.cs

@@ -1,6 +1,5 @@
 using System;
 using Xamarin.CommunityToolkit.ObjectModel;
-using Xamarin.CommunityToolkit.ObjectModel.Extensions;
 using Xamarin.Forms.Internals;
 
 namespace Xamarin.CommunityToolkit.Helpers
@@ -18,7 +17,10 @@ public LocalizedString(Func<string> generator = null)
 		public LocalizedString(LocalizationResourceManager localizationManager, Func<string> generator = null)
 		{
 			this.generator = generator;
-			localizationManager.WeakSubscribe(this, (t, sender, e) => t.OnPropertyChanged(null));
+
+			// This instance will be unsubscribed and GCed if no one references it
+			// since LocalizationResourceManager uses WeekEventManger
+			localizationManager.PropertyChanged += (sender, e) => OnPropertyChanged(null);
 		}
 
 		public string Localized => generator?.Invoke();

src/CommunityToolkit/Xamarin.CommunityToolkit/ObjectModel/ObservableObject.shared.cs

@@ -9,7 +9,7 @@
 namespace Xamarin.CommunityToolkit.ObjectModel
 {
 	/// <summary>
-	/// Observable object with INotifyPropertyChanged implemented
+	/// Observable object with INotifyPropertyChanged implemented using WeakEventManager
 	/// </summary>
 	public abstract class ObservableObject : INotifyPropertyChanged
 	{