_Cocoa Programming for Mac OS X_[1] by Aaron Hillegass is really great. It's not an iPhone book, but there's enough similarity that it'd still be a really valuable read.
To love learning. What are you trying to market? Find a job? Get a raise?
Anyways for some actionable advice: writing well is in shore supply as well as being able to give a good speech. If you are a technical person learn usability as that gets overlooked very often. (see don't make me think by Steven krug) I think anything you learn will give you a context in which to learn other material so no learning is in vain.
My end goal would be to find a new job and move to a completely new place. I like learning for the sake of learning, but learning as a means to an end (new job) is my goal in this instance.
Thanks for the reading recommendation, it definitely looks interesting.
No worries about the link. You can easily burn through that book in a few hours but the concepts are timeless.
What stuff do you know right now? Where do your interests lie? If you are halfway decent at programming in ruby/python/c++ you should be able to hammer your way into a nice job at a company of your choice. I was helping my last employer interview programmers and it was abysmal how many could not even pass a basic FizzBuzz test in the language of their choosing.
Chances are you already have all the hard skills you need.
The most useful skill is communication. Being able to "talk the talk", market yourself and come off an interesting and intelligent individual is the greatest asset somebody can have.
Also, learn another language (aim to know three). This is especially important if you happen to live in Europe where most companies are a mixed bag of various nations.
When it comes to learning another language as a marketable skill your mileage will vary massively. If you do not have other reasons for learning the language, your ROI could be negligible (or negative).
To learn a language well enough for it to be of the level required ('marketable skill' level) will take a very long time. Even then, it may be unnecessary.
I concur that communication is one of the most useful skills. My writing and public speaking always brings questions and is often a topic of conversation. That I (attempt to) speak the language of the country I live in and have knowledge of a number of others? It's never mentioned.
Try self-improvement. Improving who you are is never a bad idea and often leads you into other areas of development. It can lead you to explore new ideas and learn new skills which in turn can be marketable. Try to start off with reading "The Seven Habits of Highly Effective People". I thought this book was wonderful.
