'app' is an undeclared prefix. In AXML

Steps to reproduce 📜

1. Copy the axml from the Xamarin Android readme

<com.airbnb.lottie.LottieAnimationView
	android:id="@+id/animation_view"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	app:lottie_fileName="hello-world.json"
	app:lottie_loop="true"
	app:lottie_autoPlay="true" />

Expected behavior 🤔

Tell us what should happen

It should play the animation I’m assuming.

Actual behavior 🐛

Tell us what happens instead

Instead, it says " ‘app’ is an undeclared prefix. Line 36, position 5. "

Configuration 🔧

Version: 2.x

Platform:

• 🤖 Xamarin.Android

[MattWhiteProximity]

That makes complete sense! and works! thanks.

[clovyclov]

@MattWhiteProximity I figured it out. So “app” throws that issue because it’s an undeclared xml namespace. For example, look at your outermost element. See how it shows

xmlns:android="http://schemas.android.com/apk/res/android"

that means you are declaring “android” as a new xml namespace (xmlns). So the same must be done for “app”. So just put this on the outermost layer and you should be set

xmlns:app="http://schemas.android.com/apk/res-auto"

Be sure to clean the solution, delete the bin and obj folders, and rebuild.