Chapter 11. Simple Animations
WHAT YOU WILL LEARN IN THIS CHAPTER:
How to use the
NSTimerclass to create timers that will call methods at regular time intervals
How to perform simple animations using the
How to perform affine transformation on ImageView
How to animate a series of images using ImageView
Up to this point, the applications you have written have all made use of the standard views provided by the iPhone SDK. As Apple has reiterated, the iPad is not just for serious work; it is also a gaming platform.
In this chapter, you can have some fun and create something visual. You learn how to perform some simple animations using a timer object and then perform some transformations on a view. Although it is beyond the scope of this book to show you how to create animations using OpenGL ES, this chapter does show you some interesting techniques that you can use to make your applications come alive!
USING THE NSTIMER CLASS
One of the easiest ways to get started with animation is to use the
NSTimer class. The
NSTimer class creates timer objects, which allow you to call a method at a regular time intervals. Using an
NSTimer object, you can update an image at regular time intervals, thereby creating an impression that it is being animated.
In the following Try It Out, you learn how to display a bouncing ball on the screen using the
NSTimer class. When the ball touches the sides of the screen, it bounces off in the opposite direction. You also learn how to control the frequency ...