I got a error when running objectal example

[sloopdoom]

The error :
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '+[NSMutableArray newMutableArrayUsingWeakReferencesWithCapacity:]: unrecognized selector sent to class 0x1b854dd90'

It seems NSMutableArray has no method of " newMutableArrayUsingWeakReferencesWithCapacity" but I found it in the NSMutableArray+WeakReferences.h .

my code:
OALSimpleAudioSample * sample = [OALSimpleAudioSample alloc] ;
[sample init]; // <------ error occur