6 Beginning iOS: A Safari Guide TOPIC: FRAMEWORKS iOS applications are built using frameworks. Frameworks are bundles of dynamic libraries, header files, and other resources such as images and sounds. There are two essential frameworks. The Foundation framework is not uniquely iOS. It is a collection of common objects such as strings (NSString), numbers (NSNumber), dates (NSDate), and collections (NSArray, NSSet, etc.) that are useful regardless of platform. The second essential framework is UIKit, also known as "Cocoa Touch." It is the user interface framework for all iOS applications. In addition to introducing frameworks, this section of the guide completes the basic lessons on Objective-C by showing the Foundation framework in use. Foundation objects are present in all nontrivial iOS applications, and it is important that you see how they are used in Objective-C. The UIKit and other frameworks are presented in various sample applications and sections through all three guides. Learning Objective-C 2.0: A Hands-On Guide to Objective-C for Mac and iOS Developers, by Robert Clair, Addison-Wesley Professional o o Chapter 8. Frameworks Chapter 9. Common Foundation Classes [02:00] TOPIC: TOOLS Several tools are used in developing iOS applications. The primary tool is the IDE named Xcode. Closely related, and beginning with Xcode 4 directly incorporated into Xcode, is the Interface Builder. As its name implies, the Interface Builder is used to build the user interface for the application. As you will see across all the guides, Interface Builder is more than a simple screen painter. Another important tool in terms of iOS programming is of course the Simulator. All three devices--iPhone, iPod Touch, and iPad--can be simulated. While no substitute for the real devices, the Simulator allows for rapid development of your application.