There is a vast difference in the coding environments of an Android app and an iOS app. The tools used for coding in each environment do not share resemblance with each other. So, it would not be an exaggeration to say that a developer who is specialized in using the tools meant for building an Android app might not be familiar with the tools required to build an iOS app. This is the reason an enterprise looking for app development in both the variants hire the services of an application development firm.