(Sorry I clicked 'Accepted Answer' by mistake and can't undo it?)

Hi Quinn - we are using XCode's inbuilt toolchain. The constructor was called when we used the previous XCode toolchain, but is not called when built with XCode 16.4/26 toolchains. (Note that the comment facility here is failing to post comments, only replies)

Hi Quinn - thanks for your comprehensive replies. (I've performed the same role for Qualcomm's Augmented Reality Toolkit in the past so I appreciate the time it takes). I'll follow through your example. The only obvious difference I can see from inspection is the passing of the constant integer to the constructor() macro. We have a work-around which is to explicitly call the initialisation method before doing anything else with the library, but it'd be good to know if this is the issue for others. = Martin =