xcode 编译错误记录

Error

Undefined symbols for architecture arm64:
  "_OBJC_CLASS_$_FBSession", referenced from: someFile
ld: symbol(s) not found for architecture arm64

solution

if your Architectures and Valid Architectures are all right, 
you may check whether you have added $(inherited) , 
which will add linker flags generated in pods, to Other Linker Flags as below:

image