Can't set properties on nested classes from Xaml
android, c#, xamarin, xamarin.forms, xaml
Solution
You can't reference nested classes from `Xaml`.
You can quote me on this, or google it, but this is an universal truth. The reason is that Xaml Parsers would not be able to differentiate an Attached (Bindable|Dependency)Property from a nested class access, based on the dot sign.
In your case, move your Foo class from within CityGuide directly to the namespace and it should work.
Your xmlns declaration `xmlns:local="clr-namespace:AmsterdamTheMapV3"` is correct without the `assembly=` part as you are referring to the current assembly.
More info on a similar answer:https://stackoverflow.com/a/14546917/1063783
Some might ask why not use the `+` sign for nested class (like it's done in Reflection). The problem is that an a name containing a `+` sign is not a valid xml-element name (https://www.xml.com/pub/a/2001/07/25/namingparts.html)
Problem
The error that Xamarin gives back: Type Foo not found in xmlns clr-namespace:AmsterdamTheMapV3 The problem is that I am trying to define Foo but whatever I do it doenst work. I think that the problem is inside the xmls:local namespace. Maybe I make a stupid mistake inside my code. This is a Xamarin.forms project for windows, android and apple. Xaml file: ``` <?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="AmsterdamTheMapV3.CityGuide" xmlns:local="clr-namespace:AmsterdamTheMapV3"> <Label Text="{Binding MainText}" VerticalOptions="Center" HorizontalOptions="Center" /> <ScrollView Orientation="Vertical" HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand"> <StackLayout Orientation="Vertical" HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand" Spacing="0"> <!-- Button1 --> <Image x:Name="CityGuideButton1" Source="shopping_gray.png" Aspect="Fill" HorizontalOptions="FillAndExpand" VerticalOptions ="FillAndExpand" local:Foo.Tag="button1"> <Image.GestureRecognizers> <TapGestureRecognizer Tapped="Categorie_Onclick" NumberOfTapsRequired="1"/> </Image.GestureRecognizers> </Image> </StackLayout> </ScrollView> </ContentPage> ``` Cs file: ``` using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using Xamarin.Forms; namespace AmsterdamTheMapV3 { public partial class CityGuide : ContentPage { public CityGuide() { InitializeComponent(); } public class Foo { public static readonly BindableProperty TagProperty = BindableProperty.Create("Tag", typeof(string), typeof(Foo), null); public static string GetTag(BindableObject bindable) { return (string)bindable.GetValue(TagProperty); } public static void SetTag(BindableObject bindable, string value) { bindable.SetValue(TagProperty, value); } } async void Categorie_Onclick(Object sender, EventArgs args) { Image cmd = sender as Image; string txt = Foo.GetTag(cmd); await Navigation.PushAsync(new CategoriePage(txt)); } } } ``` I hope that somewann can help me. I can give more info if needed. thank you in advance!