_OBJ_CLASS_$_ undefined symbols error with SDLUIKitDelegate

I’m trying to compile for iOS through XCode 7+ an app that is coming up with this error since starting to use the facebook extension from haxelib (haxelib facebook rather than haxelib extension-facebook)

Undefined symbols for architecture arm64: "_OBJC_CLASS_$_SDLUIKitDelegate", referenced from: ltmp27 in libfacebook.a(a5504ceb_SDLUIKitDelegate+ExtensionFacebook.o) l_OBJC_$_CATEGORY_SDLUIKitDelegate_$_ExtensionFacebook in libfacebook.a(a5504ceb_SDLUIKitDelegate+ExtensionFacebook.o)

I’ve tried a number of things as unfortunately the main developer can’t work on the iOS part of it for some time, but I’m so far coming up short it seems. The problem occurs for both arm64 and armv7 architecture which suggests that there is a naming convention here for SDLUIKitDelegate that is wrong.

Could anyone shed any light?

Just to say, I’m not looking for a solution to necessarily be delivered to me on a plate here, but hopefully you guys know a bit more about what I need to at least look for to try and fix this problem myself.

From my long searches I can tell that the problem is that a class doesn’t seem to exist, as if it’s not included in the build, but clearly the library is being included so I’m unsure as to why it’s not picking up on what it needs to. SDL seems to be built in to the core of Openfl/Lime in terms of support… so is this just a change of name of a class?

Any help would be really appreciated.