Introduction to Xcode, Objective C, & the iOS SDK


I assume that when you began looking into building iPhone and iPad apps you did some research and came across some of the following terms:

  • Objective C
  • iOS SDK
  • Xcode

You may have wondered, “Which one of these should I study?” It can be hard to make sense of these terms and how they relate to each other so let’s clear up any confusion you might have.

What is Objective C?

If the awesome iPhone apps that you want to create were like tasty cupcakes that we wanted to bake, then Objective C would be the equivalent of the batter you would use. Objective C is a programming language. It is the code people write to make iPhone and iPad apps.

There are other programming languages that prominently feature the letter “C”. These include plain old C, C++, C#. Objective C does share a relationship with these other languages. Most notably, any C commands you type in an Objective C environment will still work. And while all of these languages share a common ancestry, the format of Objective C is different enough from its “cousins” that its not that helpful to learn one of these other languages first before getting started with iPhone programming.

What is Xcode?

To continue the cupcake metaphor, if Objective C is the cupcake batter, then Xcode is counter-top we work on. Xcode is a software tool that is provided by Apple that you will write Objective C in. Just like you may use Pages (or MS Word) to type word processing documents in, you use Xcode to write iPhone apps in using Objective C.

The great thing is that Apple provides a version Xcode to you for FREE to use. If you want the latest and greatest version, you’ll have to pay to become officially part of the developer program. But if you’re just getting started, the free version is more than sufficient.

What is iOS?

Next there is . iOS is a computer operating system. You are already familiar with operating systems. If you have a PC at home you probably are familiar with the Microsoft Windows operating system, with it’s familiar “Start” button. If you are more of an Apple user, then you may be familiar with Apple’s OSX operating system. iOS (the OS stands for “Operating System”) is another operating system. Unlike the others iOS is designed to work on mobile devices. iOS is the operating system that runs on all iPhones, iPads, and iPods. The apps you build will run on top of the iOS operating system (Yes, English majors. Saying “iOS operating system is technically redundant).

What is the iOS SDK?

Finally, there is the iOS SDK. SDK stands for “Software Development Kit.” As the name implies, it is a whole kit of tools that help you build great programs. Xcode is one of the tools in that kit. Also included in that kit is a iPhone and iPad simulator. The simulator allows you to see what your app will look like when it is running on one of those devices. Additionally, the SDK has a set of tools that help you track down bugs in your program and help you optimize your program to run as effectively as possible. In our cupcake metaphor, the iOS SDK is the entire kitchen in which you’ll be making your tasty apps

Julian Bryant