The guide promises to teach you to create a simple iOS app and learn the basics of Objective-C, the programming language for iOS apps. Note that to actually get an app published in the App store, you'll need to have an official developer account for $99 a year.
While the simple guide isn't as thorough as taking a full-fledge class in iOS programming, and you'll still need to put in some work and read the detailed resources Apple has linked to in each of the sections, it's a nice, easy-to-read starting point that's free.