Undefined symbols for architecture i386:
  "_OBJC_CLASS_$_OAConsumer", referenced from:
      objc-class-ref in SA_OAuthTwitterEngine.o
  "_OBJC_CLASS_$_OAToken", referenced from:
      objc-class-ref in SA_OAuthTwitterEngine.o
  "_OBJC_CLASS_$_OAMutableURLRequest", referenced from:
      objc-class-ref in SA_OAuthTwitterEngine.o
  "_OBJC_CLASS_$_OARequestParameter", referenced from:
      objc-class-ref in SA_OAuthTwitterEngine.o
  "_OBJC_CLASS_$_OADataFetcher", referenced from:
      objc-class-ref in SA_OAuthTwitterEngine.o
ld: symbol(s) not found for architecture i386
collect2: ld returned 1 exit status