I too am planning to set "my first iOS app" as a christmas holiday goal. debating between learning objective-c and doing it in ruby using RubyMotion. better decide quick, my holidays start friday!
Learning objective-c shouldn't be difficult as I have some (though quite dated) experience with c/c++ (as well as java, javascript, ruby, python).
resources i am considering:
http://pragprog.com/book/carubym/rubymotion
http://www.bignerdranch.com/book/ios_programming_the_big_ner...
https://itunes.apple.com/us/book/ipad-iphone-app-development...