How can I control ringer volume? I needed an app that would control the ringer volume of an iPhone. According to a developer I have been talking to, this is all good and possible on an Android phone but not on iOS. I just wanted to confirm if this is the case that it is not possible in iOS? 

If not, then is there a way around controlling the ringer settings? I'm not into developing iOS apps yet so I personally have no clue.
You can use Assistive Touch, which can be enabled in Settings > General > Accessibility to trigger Hardware Buttons. 

If you're asking from a developer perspective you should ask in Stack Overflow.