Xcode complains link error: "Undefine symbol: '_OBJC_CLASS_$_SKAdImpression'" after pod GoogleMobileAdsMediationAdColony

Question

I'm trying to add AdColony mediation into AdMob. I follow the instructions from 'https://developers.google.com/admob/ios/mediation/adcolony'.

After pod 'GoogleMobileAdsMediationAdColony', I open Xcode to test my app and get a link error:

Undefine symbol: '_OBJC_CLASS_$_SKAdImpression'

as well as a warning:

Could not find or use auto-linked framework 'AVFAudio'

I googled but got nothing.

Any suggestion? Thanks in advance.

Answer 1

SKAdImpression looks like a class that is new to iOS 14.5 so you likely need Xcode 12.5+ to contain that class definition.

I was running into the same Undefined symbol: 'OBJC_CLASS$_SKAdImpression' error under Xcode 12.4, but upgrading to 12.5 fixed for me.

Answer 2

Version 4.6.1 of the iOS AdColony SDK requires Xcode 12.5.

From the changelog:

4.6.1 (2021/04/21)

• SKAdNetwork view-through attribution support
• Build requires Xcode 12.5

This does mean that if you go back to 4.6.0 you should not need Xcode 12.5. You can do this by selecting a specific version of the 'GoogleMobileAdsMediationAdColony' pod:

pod 'GoogleMobileAdsMediationAdColony', '4.6.0.0'

You can see in the podspec here that this version uses version 4.6.0 of the AdColony SDK.

Obviously this is not a long-term solution, but as Xcode 12.5 requires Big Sur it allows a little more time before having to run an major OS update all your dev machines.