iOS App Development Portable Genius

Understanding Xcode

Xcode is a tool for converting code—text instructions—into an app that can run on an iOS device.

Apps are built from more than one kind of data. In addition to the raw binary instructions that run on the processor, apps also include sound files, graphic files that define screens, backgrounds, buttons or game tokens, font files, and other supporting information.

When you build an app, Xcode combines these elements into a single file, called the product. Most of the build process is automatic.

You have three jobs as a developer:

Creating code. Code is kept in a collection of text files. The instructions you create define how the app responds to events and circumstances, such as a finger tap, a finger drag, an incoming message or notification, an out-of-memory error, and so on. Xcode includes a code editor to help you write code.

Creating a look and feel. Xcode includes a design tool called Interface Builder, shown in Figure 2.1, that manages the look and feel of the app. You can use it to place buttons and switches, control the order in which screens appear to the user, and define the graphics the user sees.

Managing files. You’ll often have to create files using ...