App developers can make cross platform or native apps. The choice will depend on many factors. There are pros and cons for each method and I will shed some light on this to help you choose the right approach.
Cross platform apps
These are apps developed that can be used on a wide range of platforms. It is based on the concept of coding once to be run everywhere. This is to mean that the app could be used on android, iOS, blackberry or any others by developing it only once.