Like modern desktop operating systems, iOS uses a graphical user interface, or GUI. However, since it is a mobile operating system, iOS is designed around touchscreen input, rather than a keyboard and mouse. For example, applications, or “apps,” can be opened by a single tap, rather than a double-click. Different screens can be viewed by swiping your finger across the screen, rather than clicking on open windows.
Since iOS is designed to be simple and easy to use, it does not include several features found in a traditional operating system. For example, you cannot manage files and folders like you can in Mac OS X or Windows. You also have limited access to iOS system settings. Instead of modifying application preferences from within each program, most settings need to be adjusted within the Settings app. Additionally, while you can run multiple programs at once, you can only view one open program at a time.
While Apple’s iOS provides a more basic user interface than Mac OS X, each new version adds more features. For example, iOS 2 provided access to the App Store, which allowed users to download and install third-party apps on their iPhones. iOS 3 added copy and paste functionality and iPad support. iOS 4 was the first version to support multitasking and added the GameCenter feature. iOS 5 introduced the Siri voice assistant (only available on the iPhone 4S), and provided new cloud connectivity features.
The power of iOS can be felt with some of the following features provided as a part of the device.
- Facebook and Twitter
- High end processor
- Powerful APIs
- Game center
- In-App Purchase
- Wide Range of gestures
The number of users using iPhone/iPad has increased a great deal. This creates the opportunity for developers to make money by creating applications for iPhone and iPad the Apple’s App Store.
For some one new to iOS, Apple has designed an application store where the user can buy apps developed for their iOS devices. A developer can create both free and paid apps to App Store. To develop applications and distribute to the store, the developer will require to register with iOS developer program which costs $99 a year and a Mac with Mountain Lion or higher for its development with latest Xcode.
Registering as an Apple Developer
An Apple ID is most necessary if you are having any Apple device and being a developer, you definitely need it. It’s free and hence, no issues in having one. The benefits of having an Apple account are as follows −
- Access to development tools.
- Worldwide Developers Conference (WWDC) videos.
- Can join iOS developer program teams when invited.
To register an Apple account, follow the steps given below −
Step 1 − Click the link (https://developer.apple.com/programs/register/) and select “Create Apple ID”
Step 2 − Provide the necessary information, which is self explanatory as given in the page.
Step 3 − Verify your account with your email verification and the account becomes active.
Step 4 − Now you will be able to download the developer tools like Xcode, which is packaged with iOS simulator and iOS SDK, and other developer resources.
Apple iOS Developer Program
The first question that would arise to a new developer is – Why should I register for an iOS developer program? The answer is quite simple; Apple always focuses on providing quality applications to its user. If there was no registration fee, there could be a possibility of junk apps being uploaded that could cause problems for the app review team of Apple.
The benefits of joining the iOS developer program are as follows −
- Run the apps you develop on the real iOS device.
- Distribute the apps to the app store.
- Get access to the developer previews.
The steps to join the iOS developer program are as follows −
Step 1 − To register, click on the link − (https://developer.apple.com/programs/ios/).
Step 2 − Click on Enroll Now in the page that is displayed.
Step 3 − You can either sign in to your existing apple account (if you have one) or create a new Apple ID.
Step 4 − Thereafter, you have to select between Individual and Company accounts. Use company account if there will be more than one developer in your team. In individual account, you can’t add members.
Step 5 − After entering the personal information (for those who newly registers), you can purchase and activate the program by paying with the help of your credit card (only accepted mode of payment).
Step 6 − Now you will get access to developer resources by selecting the member center option in the page.
Step 7 − Here you will be able to do the following −
- Create provisioning profiles.
- Manage your team and devices.
- Managing application to app store through iTunes Connect.
- Get forum and technical support.
iOS – Xcode Installation
Step 1 − Download the latest version of Xcode from (https://developer.apple.com/downloads/)
Step 2 − Double click the Xcode dmg file.
Step 3 − You will find a device mounted and opened.
Step 4 − There will be two items in the window that’s displayed namely, Xcode application and the Application folder’s shortcut.
Step 5 − Drag the Xcode to application and it will be copied to your applications.
Step 6 − Now Xcode will be available as a part of other applications from which you can select and run.
You also have another option of downloading Xcode from the Mac App store and then install following the step-by-step procedure given on the screen.
Interface builder is the tool that enables easy creation of UI interface. You have a rich set of UI elements that is developed for use. You just have to drag and drop into your UI view. We’ll learn about adding UI elements, creating outlets and actions for the UI elements in the upcoming pages.
You have objects library at the right bottom that consists the entire necessary UI element. The user interface is often referred as xibs, which is its file extension. Each of the xibs is linked to a corresponding view controller.
An iOS simulator actually consists of two types of devices, namely iPhone and iPad with their different versions. iPhone versions include iPhone (normal), iPhone Retina, iPhone 5. iPad has iPad and iPad Retina. A screenshot of an iPhone simulator is displayed below.
You can simulate location in an iOS simulator for playing around with latitude and longitude effects of the app. You can also simulate memory warning and in-call status in the simulator. You can use the simulator for most purposes, however you cannot test device features like accelerometer. So, you might always need an iOS device to test all the scenarios of an application thoroughly.