Learn Objective-C: Day 4

Welcome to part four of this series on Objective-C. So far, we’ve looked a lot at theory and the principles and functionality of the language to get a good idea of how it works. Today, we will be making a simple class similar to the car example we looked at in previous parts of this series. Our class will take the details of a car, allowing us to get and set the values held. After today’s example you should be able to create your own classes in Xcode and toy around with them.

So far, we have had some great feedback via email, twitter and comments. Itʼs great to see so many people are interested in this subject and itʼs even better to see that so many of you are trying it out for yourself and asking some great questions. Keep it up!

Getting Started

Start by firing up Xcode and creating a new project. Under the Mac OS X separator, click Application, then click Command Line Tool. Finally, change the drop down box to set the type to Foundation.

Learn Objective-C: Day 3

Welcome to part three of this series -I hope youʼre enjoying it! Last week we looked at how we separate classes in to separate files (interface and implementation), this week weʼre going to look at classes again, but a little bit more in depth. Weʼll also take a peak at inheritance and how it works, along with variable scope.

So far, we have had some great feedback via email, twitter and comments. Itʼs great to see so many people are interested in this subject and itʼs even better to see that so many of you are trying it out for yourself and asking some great questions. Keep it up!

Learn Objective-C: Day 2

Welcome to part two of this introductory series on Objective-C. After spending last week reviewing the fundamentals of the C language upon which Objective-C is built, this week we will transition to focusing on what makes Objective-C such a great language for software development. Specifically, we will discuss the fundamentals of Object Oriented Programming (OOP) and demonstrate how to create a class and send messages to objects in Objective-C.

Object Orientated Programming

Why do we have Objective-C? Why not just use the underlying C language? The reason we have Objective-C is to give us an object oriented playground within which to build our applications. OOP is a programming paradigm that attempts to allow developers to think about software design in terms of objects and attributes instead of variables and functions. Specifically, OOP attempts to obtain data abstraction, encapsulation, modularity, polymorphism, and inheritance. The topic of OOP could easily fill a book (or a tutorial series) on its own, so instead I’ll introduce you to the basic principles by way of example.

Learn Objective-C: Day 1

Welcome to my series on coming to grips with the awesome language that is Objective-C. Throughout this small series of articles, my aim is to take you from no prior experience with Objective-C to using it confidently in your own applications. This isnʼt a rush job – so donʼt expect to just skim through the basics and be away – weʼll be going through not just the bare essentials, but also the best practices you can apply to ensure your code is the best it can be. Letʼs jump straight in!

What is Objective-C?

If youʼre reading this series then Iʼll hazard a guess that you already know, but for those of you who donʼt, donʼt worry as by the end of this part youʼll know what it is back-to-front and inside-out.

Objective-C is an object oriented language which lies on top of the C language (but I bet you guessed that part!). Itʼs primary use in modern computing is on Mac OS X as a desktop language and also on iPhone OS (or as it is now called: iOS). It was originally the main language for NeXTSTEP OS, also known as the operating system Apple bought and descended Mac OS X from, which explains why its primary home today lies on Appleʼs operating systems.

Because Objective-C is a strict superset of C, we are free to use C in an Objective-C file and it will compile fine. Because any compiler of Objective-C will also compile any straight C code passed into it, we have all the power of C along with the power of objects provided by Objective-C.

If youʼre a little confused at this point, think of it this way: everything C can do, Objective-C can do too, but not the other way around.