Undefined symbols for architecture i386

问题：ld: warning: directory not found for option '-L/Users/**/ChinaPay_SDK/libs'
Undefined symbols for architecture i386:
  "_OBJC_CLASS_$_ChinaPay_iPhone_ViewController", referenced from:
      objc-class-ref in RechargeViewController.o
      objc-class-ref in HXBindCardFirstStepViewController.o
      objc-class-ref in HXRegistFirstStepViewController.o
ld: symbol(s) not found for architecture i386

clang: error: linker command failed with exit code 1 (use -v to see invocation)

解决方案：

   1、如果是外部导入的第三方库，就在target-build setting-Library Search Paths中此库的路径删除，然后将此库在工程中的引用删除，clean一下工程，重新build,再把此库添加进去。

   2、如果是官方发布的库framework文件，就在target-build setting-framework Search Paths中此库的路径删除，clean一下工程，重新build。