Xamarin Forms.Xaml.XamlParseException

Question

I am creating a xamarin behaviour to validate an email id, therefore I created the behaviour file and tried to localise it in XAML file but I get the below error

Answer 1

This could be related to a known linking issue - where Xamarin compiler ends up linking out classes (from external assemblies) that have references only in XAML.

Looks like EmailBhvr might be getting linked out by the compiler. There are couple of links that talk about this:

1. Extending Control plugins > Getting Started
2. Force assembly linking

There are a lot of options to resolve this:

1. Add a static Init method in each class as mentioned here in "Getting started" section here

   // this ensures the class does not get 
   // linked out in the application we add this assembly to.
   public static void Init() { }
   

2. Or, preserve code using preserve attributes on Android, and iOS

   public class Example
   {
        [Android.Runtime.Preserve]
        public Example ()
        {
        }
   }
   

3. Or, use Custom linking.

4. Or, update project configuration to not link. Android, and iOS. Not a recommended option though.