Undefined symbols for architecture x86_64

Need help!

XCode 11.
Ios.

I've added C++ library. I get the error:

Code Block Undefined symbols for architecture x86_64: "FUN_Init(int, SInitParam*)", referenced from:   -[AppDelegate application:didFinishLaunchingWithOptions:] in AppDelegate.old: symbol(s) not found for architecture x86_64

I added this library from another project. But if I build "mother" project, I will get the same error.
Undefined symbols for architecture x86_64
 
 
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