Well, I have read a lot about ads in ios app. It seems there are a lot of providers. What I understand it seems that adMob is the biggest/most used. iAds is provided by Apple itself, but what I've heard it seems you can get less money for it and, especially, it seems it works bad/generates less money in specific countries (I read about Sweden market).
My real question is: You can integrate multiple ads-provider in your app, cant you? Is it common for those that release ios-apps to have 2 or more ads-provider?