When archiving, such en error occurs:
Projects/Dossier/MultiDocument/Helpers/GAD/libGoogleAdMobAds.a(GADGestureCFiles.o) duplicate symbol _tohex in:
If you're using the Admob v6.2 library make sure you're NOT using the -all_load linker flag, use the -ObjC linker flag instead.
-all_load
-ObjC