Describe Key Ingredients Needed

Among one of many reasons to target the Android platform, 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. 

500 words, 2 references need.