This course was integral in kicking off my career over a decade ago. I think there's no better way to learn to build an iOS app, and the fact that it's free is a true gift. Pre-reqs are in the first lecture:

-Experience writing code (100% of the work in this course involves programming) -At least CS106A (Programming Methodology) + CS106B or X (Programming Abstractions) and CS107 (Computer Organization & Systems); CS108 (Object Oriented Programming), CS43 (Functional Programming Abstractions), CS11O (Principles of Computer Systems), CS147 (Introduction to Human Computer Interaction Design) are awesome! -Know some "structured" programming paradigm, e.g. OOP or Functional Programming -Preferably you know more than one language (cause you're gonna learn a new one here!)