ArgumentNullException on iOS for animation using ImageAssetsFolder

🐛 Bug Report

After updating from v3.1.3 to v4.0.4 I get an exception in animation using ImageAssetsFolder on iOS. The animation worked fine in v3.1.3.

The animation plays fine in the Android version of my app on v4.0.4 (I am using the Xamarin.Forms component).

The exception I get is:

System.ArgumentNullException: Value cannot be null.
Parameter name: bundle
  at Airbnb.Lottie.LOTComposition.AnimationNamed (System.String animationName, Foundation.NSBundle bundle) [0x00011] in /Users/martijn/Documents/OpenSource/LottieXamarin/Lottie.iOS/obj/Release/xamarin.ios10/ios/Airbnb.Lottie/LOTComposition.g.cs:137
  at Lottie.Forms.Platforms.Ios.AnimationViewExtensions.GetAnimation (Lottie.Forms.AnimationView animationView) [0x00059] in C:\Users\mhvdi\Documents\OpenSource\LottieXamarin\Lottie.Forms\Platforms\Ios\AnimationViewExtensions.cs:24
  at Lottie.Forms.Platforms.Ios.AnimationViewRenderer.OnElementChanged (Xamarin.Forms.Platform.iOS.ElementChangedEventArgs`1[TElement] e) [0x000f6] in C:\Users\mhvdi\Documents\OpenSource\LottieXamarin\Lottie.Forms\Platforms\Ios\AnimationViewRenderer.cs:50
  at Xamarin.Forms.Platform.iOS.VisualElementRenderer`1[TElement].SetElement (TElement element) [0x00172] in D:\a\1\s\Xamarin.Forms.Platform.iOS\VisualElementRenderer.cs:296
  at Xamarin.Forms.Platform.iOS.VisualElementRenderer`1[TElement].Xamarin.Forms.Platform.iOS.IVisualElementRenderer.SetElement (Xamarin.Forms.VisualElement element) [0x00000] in D:\a\1\s\Xamarin.Forms.Platform.iOS\VisualElementRenderer.cs:158
  at Xamarin.Forms.Platform.iOS.Platform.CreateRenderer (Xamarin.Forms.VisualElement element) [0x00014] in D:\a\1\s\Xamarin.Forms.Platform.iOS\Platform.cs:227
  at Xamarin.Forms.Platform.iOS.VisualElementPackager.OnChildAdded (Xamarin.Forms.VisualElement view) [0x0003e] in D:\a\1\s\Xamarin.Forms.Platform.iOS\VisualElementPackager.cs:115
  at Xamarin.Forms.Platform.iOS.VisualElementPackager.Load () [0x0001e] in D:\a\1\s\Xamarin.Forms.Platform.iOS\VisualElementPackager.cs:49
  at Xamarin.Forms.Platform.iOS.VisualElementRenderer`1[TElement].SetElement (TElement element) [0x0012e] in D:\a\1\s\Xamarin.Forms.Platform.iOS\VisualElementRenderer.cs:283
  at Xamarin.Forms.Platform.iOS.VisualElementRenderer`1[TElement].Xamarin.Forms.Platform.iOS.IVisualElementRenderer.SetElement (Xamarin.Forms.VisualElement element) [0x00000] in D:\a\1\s\Xamarin.Forms.Platform.iOS\VisualElementRenderer.cs:158
  at Xamarin.Forms.Platform.iOS.Platform.CreateRenderer (Xamarin.Forms.VisualElement element) [0x00014] in D:\a\1\s\Xamarin.Forms.Platform.iOS\Platform.cs:227
  at Xamarin.Forms.Platform.iOS.VisualElementPackager.OnChildAdded (Xamarin.Forms.VisualElement view) [0x0003e] in D:\a\1\s\Xamarin.Forms.Platform.iOS\VisualElementPackager.cs:115
  at Xamarin.Forms.Platform.iOS.VisualElementPackager.Load () [0x0001e] in D:\a\1\s\Xamarin.Forms.Platform.iOS\VisualElementPackager.cs:49
  at Xamarin.Forms.Platform.iOS.ScrollViewRenderer.SetElement (Xamarin.Forms.VisualElement element) [0x00087] in D:\a\1\s\Xamarin.Forms.Platform.iOS\Renderers\ScrollViewRenderer.cs:71
  at Xamarin.Forms.Platform.iOS.Platform.CreateRenderer (Xamarin.Forms.VisualElement element) [0x00014] in D:\a\1\s\Xamarin.Forms.Platform.iOS\Platform.cs:227
  at Xamarin.Forms.Platform.iOS.VisualElementPackager.OnChildAdded (Xamarin.Forms.VisualElement view) [0x0003e] in D:\a\1\s\Xamarin.Forms.Platform.iOS\VisualElementPackager.cs:115
  at Xamarin.Forms.Platform.iOS.VisualElementPackager.Load () [0x0001e] in D:\a\1\s\Xamarin.Forms.Platform.iOS\VisualElementPackager.cs:49
  at Xamarin.Forms.Platform.iOS.PageRenderer.ViewDidLoad () [0x0008f] in D:\a\1\s\Xamarin.Forms.Platform.iOS\Renderers\PageRenderer.cs:237
  at at (wrapper managed-to-native) ObjCRuntime.Messaging.IntPtr_objc_msgSendSuper(intptr,intptr)
  at UIKit.UIViewController.get_View () [0x0002a] in /Library/Frameworks/Xamarin.iOS.framework/Versions/14.0.0.0/src/Xamarin.iOS/UIKit/UIViewController.g.cs:3267
  at Xamarin.Forms.Platform.iOS.PageRenderer.get_NativeView () [0x00000] in D:\a\1\s\Xamarin.Forms.Platform.iOS\Renderers\PageRenderer.cs:103
  at Xamarin.Forms.Platform.iOS.PageRenderer.SetElement (Xamarin.Forms.VisualElement element) [0x0003d] in D:\a\1\s\Xamarin.Forms.Platform.iOS\Renderers\PageRenderer.cs:119
  at Xamarin.Forms.Platform.iOS.Platform.CreateRenderer (Xamarin.Forms.VisualElement element) [0x00014] in D:\a\1\s\Xamarin.Forms.Platform.iOS\Platform.cs:227
  at Xamarin.Forms.Platform.iOS.Platform.AddChild (Xamarin.Forms.VisualElement view) [0x00027] in D:\a\1\s\Xamarin.Forms.Platform.iOS\Platform.cs:339
  at Xamarin.Forms.Platform.iOS.Platform.WillAppear () [0x0003c] in D:\a\1\s\Xamarin.Forms.Platform.iOS\Platform.cs:325
  at Xamarin.Forms.Platform.iOS.PlatformRenderer.ViewWillAppear (System.Boolean animated) [0x00018] in D:\a\1\s\Xamarin.Forms.Platform.iOS\PlatformRenderer.cs:95
  at at (wrapper managed-to-native) UIKit.UIApplication.UIApplicationMain(int,string[],intptr,intptr)
  at UIKit.UIApplication.Main (System.String[] args, System.IntPtr principal, System.IntPtr delegate) [0x00005] in /Library/Frameworks/Xamarin.iOS.framework/Versions/14.0.0.0/src/Xamarin.iOS/UIKit/UIApplication.cs:86
  at UIKit.UIApplication.Main (System.String[] args, System.String principalClassName, System.String delegateClassName) [0x0000e] in /Library/Frameworks/Xamarin.iOS.framework/Versions/14.0.0.0/src/Xamarin.iOS/UIKit/UIApplication.cs:65
  at Blueye.App.iOS.Application.Main (System.String[] args) [0x00001] in /Users/follesoe/source/BlueyeApp/iOS/Main.cs:12

Looking at the source code, the relevant lines are: https://github.com/Baseflow/LottieXamarin/blob/develop/Lottie.Forms/Platforms/Ios/AnimationViewExtensions.cs#L24

Expected behavior

The animation should play on iOS the same way it does on Android, and in version 3.1.3 on iOS.

Reproduction steps

If needed I can provide the specific animation later. My XAML element looks like this:

<lottie:AnimationView
	x:Name="animationView" 
	BackgroundColor="Transparent"
	Animation="{Binding Animation}"
	RepeatMode="Infinite"
	AutoPlay="true"
	VerticalOptions="Center" 
	HorizontalOptions="Fill"
	Margin="40"
	WidthRequest="240"
	HeightRequest="220"/>

The ImageAssetFolder property is set like this: animationView.ImageAssetsFolder = "LottieAnimations/Images";.

On iOS, the images are added to the asset catalog. Could this perhaps be the source of the issue?

Configuration

Version: 4.04

Platform:

• 📱 iOS
• 🤖 Android
• 🏁 WPF
• 🌎 UWP
• 🍎 MacOS
• 📺 tvOS
• 🐒 Xamarin.Forms

[martijn00]

I’ve added some checks, so maybe this works a bit better now. Can you test?

[follesoe]

I think we can conclude that the ImageAssetsFolder was ignored in the 3.0 release. Tested setting the property on iOS and I do not get a runtime exception in version 4.0.6.