For those who lack the time, knowledge, or incentive to write their own code, there are any number of app publishing resources available. The free ones are somewhat limited in the degree to which you can customize the apps you create, or place ads in the apps you create. The free software/service companies offer their paid premium versions for those whose needs aren’t met by the no-cost version. A few examples are given below.
http://www.teachthought.com/technology/5-tools-teachers-create-publish-apps/