For my fellow iPhone app developers: A way to manage and send out your promo codes with ease. It's called Tokn. You do need a Mac to use it. Check it out! It's also possible to allow users of your iPhone app to gift your app within the app itself. You just need a bit of code and your app ID.
iOS is the operating system for Apple's iPhone, Touch and iPad (that name still makes me cringe). Want to learn how to build apps for these devices? Take a class. Udemy offers a straight-forward one.
iPhone app development is also now offered to high school students! MakeGamesWith.us offers an online tutorial for those with some object-oriented programming skills (found in many AP computer science classes). The site teaches Objective-C.
Note: a Mac is required.