David Mark

Taps, Touches, and Gestures

The screens of the iPhone, iPod touch, and iPad—with their crisp, bright, touch-sensitive display—are truly things of beauty and masterpieces of engineering. The multitouch screen common to all iOS devices is one of the key factors in the platform’s tremendous usability. Because the screen can detect multiple touches at the same time and track them independently, applications are able to detect a wide range of gestures, giving the user power that goes beyond the interface.

Basic Data Persistence

So far, we’ve focused on the controller and view aspects of the MVC paradigm. Although several of our applications have read data out of the application bundle, none of them has saved data to any form of persistent storage—nonvolatile storage that survives a restart of the computer or device. So far, with the exception of Application Settings (in Chapter 12), every sample application either did not store data or used volatile (i.e., nonpersistent) storage. Every time one of the sample applications launched, it appeared with exactly the same data it had the first time you launched it.

Welcome to the Jungle

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Handling Basic Interaction

Our Hello World application was a good introduction to iOS development using Cocoa Touch, but it was missing a crucial capability—the ability to interact with the user. Without that, our application is severely limited in terms of what it can accomplish.

Navigation Controllers and Table Views

In the previous chapter, you mastered the basics of working with table views. In this chapter, you’ll get a whole lot more practice because we’re going to explore navigation controllers.

Tab Bars and Pickers

In the previous chapter, you built your first multiview application. In this chapter, you’re going to build a full tab bar application with five different tabs and five different content views. Building this application will reinforce a lot of what you learned in Chapter 6. Now, you’re too smart to spend a whole chapter doing stuff you already sort of know how to do, so we’re going to use those five content views to demonstrate a type of iOS control that we have not yet covered. The control is called a picker view, or just a picker.

More User Interface Fun

In Chapter 3, we discussed MVC and built an application using it. You learned about outlets and actions, and you used them to tie a button control to a text label. In this chapter, we’re going to build an application that will take your knowledge of controls to a whole new level.

Application Settings and User Defaults

All but the simplest computer programs today have a preferences window where the user can set application-specific options. On Mac OS X, the Preferences… menu item is usually found in the application menu. Selecting it brings up a window where the user can enter and change various options. The iPhone and other iOS devices have a dedicated application called Settings, which you no doubt have played with any number of times. In this chapter, we’ll show you how to add settings for your application to the Settings application and how to access those settings from within your application.