AdMob singleton class method import [on hold]

For iAd i coded my own singleton iAd class however, for AdMob I found a tutorial from Google developers...

http://ift.tt/1wKOjKo

I needed to get the AdMob to work in a different ViewController called ViewControllerTWO.

So I imported #import "GADMasterViewController.h" into ViewControllerTWO and I placed...

- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
shared = [GADMasterViewController singleton];
[shared resetAdView:self];
}

However, i'm receiving 2 errors:

1)No known class method for selector 'singleton'

2)No visible 'GADMasterViewController' declares selector 'resetAdView:'

The problem appears to be with the line "shared = [GADMasterViewController singleton];"

I don't understand what the problem could be, since the rest of the code seems to be OK, following when i imported AdMob from one VC to another.

Is the syntax of the critical line wrong? Or do I need to add additional code in connection with it to clarify things?