AdMob code not shows adbanner in screen

i try to run the downloaded code from admob, but that not shows adbanner in screen, even i uses publisher id in pice of code.

bannerView_.adUnitID = MY_B开发者_开发百科ANNER_UNIT_ID; Please answer.

Enable test ads to check whether the problem is with your code or with AdMob:

GADRequest.isTesting = YES;

Do what jnic suggests. Also, check if there is a message from AdMob in the console. There might be a message that says not showing ads is normal.