Even if you have it in a layer your ads will be drawn within their own UIView, so moving the layer would have little to no effect, the ads are part of the iOS view hierarchy, the whole cocos2dx view is just a single view, regardless of your layers, sprites, etc. So you’ll need to stack a new view on top which is your ads, and your game will be under it.
I hope that makes sense… But for the most part, pull down the code from the bitbucket I posted, and then try the methods for the hide / show, and see if that’s what you want. You can even extend it to not use iAds if you wish to not have them, (although it will fall back automatically anyway, but if you didn’t want to include the sdk).
To enable / hide the ads i’m just using NSNotifications, so I scribbled up a small ‘bridge’ class for that, I’ve added that to the repo as well.
Hope that helps