Error in compiling

In Xcode 7.2.1 , I am getting error when I compile project which says :-

Undefined symbols for architecture x86_64:

"_OBJC_CLASS_$_AssistSDK", referenced from:

objc-class-ref in VideoCallViewController.o

ld: symbol(s) not found for architecture x86_64

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

This is what currently I have for architecture settings perspective in my App :-

Architectures : Standard Architectures(armv7, arm64) - $(ARCHES_STANDARD)

Base SDK : Latest iOS(9.2)

Valid Architectures: arm64, armv7, armv7s

IOS Deployment Target: iOS 7.1

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