It's so much easier when you already know how to program anything.
I was a Perl dev and dabbled in Java. I was forced at my job to learn iOS and produce a specific app in less than 3 weeks.
Wasn't pretty, but working under pressure can be good motivation too.
Pretty similar situation here. Was told to experiment with mobile apps first, but after deciding to use my own computer went native instead. From a background in PHP and only very limited knowledge of how Obj-C works, I managed to get an app mostly finished in the best part of a fortnight.
The biggest hurdle was actually trying to create a native form; something which is remarkably difficult to find good resources for compared to other things.
Had I tried to learn in my own time, without the pressure of having to get something working at all, I would have spent months reading textbooks and learning how to write basic hello world apps.
Instead, I made more progress than I could ever have imagined just by being given a challenge and an idea of what to make. And that's sometimes the best learning experience you can get.
