具体错误：
Undefined symbols for architecture x86_64:
“OBJC_CLASS$_AFHTTPSessionManager”, referenced from:
objc-class-ref in LHHttpTool.o ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code
1 (use -v to see invocation)
解决
出现类似 Undefined symbols for architecture x86_64 错误，一般是缺少包的引用，请尝试xcode–>项目–>Build phases–>Link Binaray With Libraries–>选择“+”号–>在弹出的对话框中搜索缺少的包。引用即可。
我的是缺少 libAFNetworking.a 加入即可
