I got this error when integrating Applovin SDK:
Undefined symbols for architecture armv7: "_OBJC_CLASS_$_ALSdk", referenced from: objc-class-ref in AppDelegate.o
"_OBJC_CLASS_$_ALInterstitialAd", referenced from:
objc-class-ref in ViewController.o ld: symbol(s) not found for architecture armv7 clang: error: linker command failed with exit code 1 (use -v to see invocation)