Undefined symbols for architecture x86_64: “OBJC_CLASS$_AFHTTPRequestOperationManager”, referenced from: type metadata accessor for __ObjC.AFHTTPRequestOperationManager in UserManager.o ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation)
使用Pod降级AFNetworking后，会发生这样的错误，重新安装AFN都不行。
解决办法：
在自己的工程Build Phases的Link Binary With Libraries中添加
