Is -ObjC linker flag required for RapidEars?

[rikk]

I have a working OpenEars 2.0.3 app. I want to add RapidEars and have followed instructions, EXCEPT for the -ObjC linker flag. It compiles and links fine.

When I run, I get:

2015-05-04 … Bleeper[…] -[OEPocketsphinxController startRealtimeListeningWithLanguageModelAtPath:dictionaryAtPath:acousticModelAtPath:]: unrecognized selector sent to instance 0x1740b2660

2015-05-04 … Bleeper[…] *** Terminating app due to uncaught exception ‘NSInvalidArgumentException’, reason: ‘-[OEPocketsphinxController startRealtimeListeningWithLanguageModelAtPath:dictionaryAtPath:acousticModelAtPath:]: unrecognized selector sent to instance 0x1740b2660’

If I add -ObjC, it runs fine.

So, can someone explain to me why this matters? I suspect that this means that something else is wrong in my build settings.

Thanks,
Rikk

[rikk]

Answering my own question (I think):

I have probed a bit more inside of the OEPocketsphinxController+RapidEars.h and saw that RapidEars is using Objective-C `category’ feature to extend the class. This was a great opportunity for me to learn about the ‘category’ feature of Objective-C.

https://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/ProgrammingWithObjectiveC/CustomizingExistingClasses/CustomizingExistingClasses.html

As I researched more, I found this on Stack Overflow:
http://stackoverflow.com/questions/2567498/objective-c-categories-in-static-library

And doc from Apple:
https://developer.apple.com/library/mac/qa/qa1490/_index.html

ANSWER: Yes, the -ObjC linker flag is indeed required when using any plugins for OpenEars. :-D

[Halle Winkler]

Hi rikk,

It says in the documentation and tutorial that it is necessary to add -ObjC.

[gregorym]

How do I add the -ObjC flag to xcode? Is it just “-ObjC” In the “Other Linker Flags” or is it something more specific?

[Halle Winkler]

Hello,

That’s correct, in the app target build settings.

[Author]

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