如何解决从ios4.2到ios5的更新问题？

Question

我尝试更改4到5的应用程序，在构建过程中它会显示如下所示的错误 任何人都可以为此提供解决方案吗？

Undefined symbols for architecture i386:
  "_OBJC_CLASS_$_FlurryAPI", referenced from:
      objc-class-ref in NewsViewController.o
      objc-class-ref in NewsDetailViewController.o
      objc-class-ref in ArchiveIndvidualView.o
      objc-class-ref in ArchiveMenuViewController.o
      objc-class-ref in ReleaseDetailView.o
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)