Is the work with phone functions the same under different versions of Android? Under different versions of iOS?

Question

Mobile development

I need to write a mobile server application that provides a legitimate client with access to phone functions - working with phone calls (answer/hang up incoming calls, initiating outgoing calls), SMS, GPRS, GPS, accelerometer and compass data, phone book, etc.
The task is to use Moverio glasses ( habrahabr.ru/post/145462/) as a mobile phone interface. I have been developing mobile applications for over 10 years (I have worked with J2ME, Brew, Maemo), but I still have little experience in programming for Android, and even less for iOS.
In this regard, the question arose - if you write this application for Android 2.2 - will it work under newer versions of Android? Which model for Android would be worth taking - in order to spend a minimum of money on the one hand, and at the same time, so that the program written for the purchased device would also work on devices with more recent OS versions? Same question for iOS.

Answer 1

If the application is written for 2.2 then it will work on 2.2+. I ask you to pay attention to the fact that in versions 4.0+ there are no some elements, otherwise, for example, the menu button, etc. And the design for 3.0 should have been different, after all, this system for tablets.
As such, almost the entire architecture of Android is backward compatible (I have not yet encountered any backward non-compatibility situation in practice).
In most cases, if you use the "standard" ways of displaying the View, then (theoretically) it will work everywhere. Problems are often with screen sizes and graphics.
I myself do not develop for iOS, but I heard from a colleague that some restrictions are added with higher versions.

Answer 2

Just keep in mind that iOS will not give you access to calls (answer/hang up) and SMS. Only make an outgoing call and initialize an SMS, the sending of which must be confirmed by the user.