admob unity plugin ios Undefined symbols for architecture arm64:

I have a project that includes Admob unity plugin , i build it for ios. I followed the instruction below using the cocoa pods method to set the plugin up.

i build the project in Xcode 7 but get build errors below. I been trying to get it to build for a day, any help appreciated.

Undefined symbols for architecture
arm64:
“_kGADAdSizeSmartBannerLandscape”,
referenced from:
-[GADUBanner initWithSmartBannerSizeAndBannerClientReference:adUnitID:adPosition:]
in GADUBanner.o
OBJC_CLASS_GADBannerView", referenced from: objc-class-ref in GADUBanner.o "_OBJC_CLASS__GADRequest”, referenced
from:
objc-class-ref in GADURequest.o “OBJC_CLASS_GADInterstitial", referenced from: objc-class-ref in GADUInterstitial.o "_kGADAdSizeSmartBannerPortrait", referenced from: -[GADUBanner initWithSmartBannerSizeAndBannerClientReference:adUnitID:adPosition:] in GADUBanner.o "_OBJC_CLASS__GADExtras”, referenced
from:
objc-class-ref in GADURequest.o “_GADAdSizeFromCGSize”, referenced
from:
-[GADUBanner initWithBannerClientReference:adUnitID:width:height:adPosition:]
in GADUBanner.o ld: symbol(s) not
found for architecture arm64 clang:
error: linker command failed with exit
code 1 (use -v to see invocation)

Did you ever resolve this issue? I am struggling with similar Admob Unity errors in Xcode.