• 10 heures
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Mis à jour le 27/04/2023

What is iOS?

Welcome to the course! Let's start by exploring the iOS ecosystem.

What's iOS exactly?

It is a three-letter abbreviation that stands for following:

  • The first letter - "i" - is the famous "i" that appears in other Apple product names: iPod, iPhone, iPad, etc. 

  • The other two letters - "OS" - stand for "Operating System."

Operating System

What is an operating system?

Let’s take look at a computer in general. It’s defined by two types of components: hardware and software.

Hardware is represented by physical components that can be touched, i.e. a screen, a keyboard, or circuit boards with electronic chips.

Software, on the other hand, is a virtual component, i.e. the visuals displayed on a screen, the data stored in memory, and all the logic behind the scenes.

A principle circuit board is called motherboard. It is a hardware hub that links all the core electronic components of a computer. In simple terms, after a computer starts up, it loads a piece of complex software called an operating system.  Windows or Android, for instance, are very common examples of operating systems.

All other pieces of software that run on a computer are called applications or apps for short. Operating systems are responsible for managing all the applications and act as a linker between all the apps and hardware components.

Here's a schematic representation of a computer:

So what's iOS?

iOS is an operating system as well. While some other operating systems such as Windows or Android can be used on a various number of devices, iOS is specific to only 3 types of Apple's mobile devices: iPhone, iPad and iPod Touch.

iOS is one of 4 operating systems serviced by Apple: watchOS, tvOS, iOS and macOS.

Apple's 4 operating systems
Apple's 4 operating systems

The good news is that by learning iOS, you will soon be able to easily expand your development skills onto other operating systems and thus create applications for Apple Watch, Apple TV or Mac!

iOS evolution

Like any progressive software, iOS has evolved tremendously since the very first release. Each new major innovation resulted into a new version. Today, we have reached the version of iOS 11. It's come a long way!

Here is a brief summary of iOS versions with the key innovations brought by each iteration:

iOS version history
iOS version history

As you can see, starting in 2011, a new version started coming out every year in the fall.

These innovations are announced at the Apple WorldWide Developers Conference (WWDC) which takes place every year in June. At this time, developers gain access to beta versions of the new software including operating systems and the Software Development Kit (SDK), so that they can experiment with the new features and start adapting their applications before the public release.

The public release occurs after the Apple's Keynote event that takes place every year in September. In addition to making all the new software available to everyone, this event is an opportunity for Apple to present its latest hardware innovations: maybe a new iPhone, iPad, Apple Watch, Apple TV, or Mac.

The key Apple events are therefore:

  • In June at WWDC, when Apple announces new software available for developers.

  • In September at the Keynote, when Apple announces new hardware and provides new software for everyone.

Mark these events in your calendar! It's essential for an iOS developer to keep up to date with the latest news. Otherwise, your knowledge will quickly become obsolete or incomplete.

Shortly after WWDC, Apple makes all the presentations available to Apple developers. I highly recommend watching them all to keep yourself in the loop. [Link to the videos?]

iOS device evolution

As we established earlier, iOS is the operating system of three device types: iPhone, iPad and iPod Touch.

Let's briefly review the historical milestones of each type.

The first appearance of the devices:



iPod Touch


Release date

June 29, 2007

September 5, 2007

April 3, 2010

It's been over 10 years since the beginning of this device evolution, and each device has evolved as well as expanded within its type.

iPod Touch

Let's start with the simplest device. The iPod Touch is the cousin of the iPhone, however, as the name indicates, it's only an iPod (5th & 6th generation). Compared to the same generation iPhone, it's thinner and less expensive, though it lacks some hardware features. The key distinction is that it has no SIM card support and, therefore, is not capable of making calls or exchanging messages over a cellular network.


The iPhone is by far the most popular mobile product sold by Apple. iPhone users in particular are always eager to upgrade to new devices as soon as they become available. This can be used as a suggestion to iOS developers to direct their efforts towards primarily to developing for iPhones.

The following diagram presents the evolution of the iPhone:

iPhone model history
iPhone model history

What's next? We'll find out in September 2018!

Throughout the years, new models range in innovations from dramatic redesign in appearance and technology to partial improvements compared to their immediate ancestors.

Some models are designed to accommodate a particular market need. For instance, iPhone 5C was created to serve buyers looking for a lower price range. This allowed Apple to expand their sales in emerging markets like China.

The iPhone SE, which reverts back in size to that of the iPhone 5, was produced to satisfy those who find the new generation of smartphones too large.


The latest iPad!
The latest iPad!

This family is the most sophisticated, as it has expanded and transformed into a number of subfamilies: iPad, iPad Air, iPad Mini, and iPad Pro. The release circle of each family is also less consistent. Here's a rough summary of the iPad evolution:


iPad 1 -  4

iPad Air 1, 2

iPad Mini 1 - 4

iPad Pro

iPad 2017

First release date

April 2010

November 2013

November 2012

November 2015


Latest release date

November 2012

October 2014

September 2015



Screen sizes




9.7", 10.5", 12.9"


Defining characteristics

Original iPad

An advanced version that replaced the original iPad

A smaller version of the iPad, therefore more portable

An iPad for professional use. It can be considered as powerful as a computer and supports Apple Pencil.

An iPad more powerful than iPad Air 2 but less powerful than iPad Pro

*at the time of writing, aforementioned models have been announced by Apple but are not yet released on the market.

iOS 11

In this course, we will focus on the latest version of iOS: iOS 11. This will cover a wide range of the devices that are still available on the market:

  • iPod Touch (6G)

  • iPhones (iPhone 5 and later)

  • iPad Air, iPad Mini, iPad Pro, and iPad 2017

Let's recap!

  • iOS is the operating system for the following devices: iPhone, iPad and iPod Touch.

  • A new version of iOS is released every year.

  • New device models come out every year.

  • There are 2 major Apple events that you must follow: WWDC in June and the Keynote in September.

Now that we know enough about the ecosystem, let's explore the tools and start developing applications!

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