I have been doing a lot of research and so far most of them say that charging for an app is not a good idea. But what about ads then? Should I include ads in my new iPhone app? Or should I go with a version with ads and without them?
Mobile ads can bring money from impressions and clicks. This option is beneficial for games and other apps, which keep users' attention during the long period of time, in other cases they won’t generate too much but will help ease the pain a little bit. You can use iAd or AdMob for implementing mobile ads.
But remember that mobile ads can annoy your customers, so be careful. Another way to gain money from your app is to engage sponsors and put their logos on the separate app page http://techcrunch.com/2012/07/08/8-ways-mobile-developers-can-make-the-most-money-on-their-apps/