I'm principally an iOS developer, and currently the mobile lead at my company (working on both iOS and Android.) I've been working since 2008 in mobile development, starting with JavaME, Blackberry and Nokia Symbian, before firmly becoming an iOS fan, although being co-developer for Android development provides an interesting counter-point...

I've worked on loads of client architectures using REST and socket APIs. I've also picked up lots of experience in interfacing closely with various UAV (camera drone) SDKs. So I'm a little obsessed with anything that makes asynchronous coding life easier (Reactive coding!)