solved I’m studying for my Computer Science class and need an

I’m studying for my Computer Science class and need an explanation.

Among one of many reasons to target the Android platform for app development, first and foremost is cost. On average you can get an Android smartphone for a fraction of the cost of an iPhone. They may not have commensurate features, but thrift is a major component for new smartphone buyers. Next is flexibility.    Developers can often find on cheap and imported Android devices a version of Google Play that is maintained by the manufacturer.  Developers should develop as if they expect their app to be available to all Android devices.

Besides cost, why should mobile app developers target the Android platform?
Why is Android competition to itself?
Describe key ingredients needed to create mobile applications on the iOS platform.