Category Conflict: instance method in category from conflicts with same method from another category

Question

There are two situations, that I am aware of, that cause the following errors:

ld: warning: instance method 'resetAudioSystem' in category from /opentok-ios-sdk/Opentok.framework/Opentok(OTPublisher+AudioSnoop.o) conflicts with same method from another category
ld: warning: instance method 'attachAudioSnoopBlock:' in category from /opentok-ios-sdk/Opentok.framework/Opentok(OTPublisher+AudioSnoop.o) conflicts with same method from another category
ld: warning: instance method 'setVideoSnoopDelegate:' in category from /opentok-ios-sdk/Opentok.framework/Opentok(OTPublisher+VideoSnoop.o) conflicts with same method from another category

Possibility 1: A category instance method is declared twice. (Described here: SO)

But, When I do a search of any of the 3 instance methods (in Xcode or Grep) I do not find it declared twice.

Possibility 2: Accidentally importing a .m file. (Described here: SO)

But, I checked all my imports and I only import the framework once in the whole project. Also, only shows up once in Build Phases.

My program runs without crashing, presumably because the last category definition added is used and it happens to be correct. (Source)

Question 1: Is there a way to tell, prior to its addition, where the two categories are located?

Question 2: Any other ideas about how to resolve this?

Note: The Opentok Framework is a binary

Occurs in :

xcode 4.6 & xcode 5

iOS6 & iOS7

Novotny

Check your search paths. Build Settings > Search Paths. I have had similar issues in the past and most of the time it came down to the Search Path. – Photoemission

Is the selected answer correct? The highest voted seems like the correct one to me. – Glauconite

Answer 1

This look like a linker bug. Maybe the SDK got linked more than once, or -ObjC is missing/present where it should not be. Check linker flags. Try deleting all OpenTok frameworks, make sure its missing in your projects, then re-download it and install again.

Odeen

Answer 2

I had this warnings because I accidentally imported the implementation file of a category instead of it's header file. So:

wrong: #import 'MyClass+MyCategory.m'

right: #import 'MyClass+MyCategory.h'

Tynes

Answer 3

I had this error, because I literally pasted my methods' implementation to header file (*.h). It worked well however; the only symptom - warnings.

Check whether your implementation is in correct (*.m) file.

Hyetography

Answer 4

In my case the header file containing the categories was imported twice for a class. It wasn't obvious because another header file also imported the same header. In other words

//Class_with_warnings.h:
#import "Offending_Header.h" // import #1
#import "Class_A.h"          // import #2

//Whereas Class_A.h:
#import "Offending_Header.h" // import #2

Izmir