Undefined symbols for architecture x86_64: "_OBJC_CLASS_$_CMMotionManager", referenced from: objc-class-ref in GooglePlus(GPPSpamSignal.o)

Undefined symbols means usually that you are missing an import statement. Looks like you are using CMMotionManager is part of CoreMotion, so you might need to :

#import <CoreMotion/CoreMotion.h>

And verify that you have added CoreMotion to your project

As CMMotionManager is part of CoreMotion framework, simply include the framework in your build in Xcode in "target"'s Build Phases: "link with": add "+" "CoreMotion.framework"