What Is Core Animation? - Core Animation - page 6

Core Animation provides a slew of
different layers that help you achieve
different functions based upon your
application needs. If you need to play a
movie, for example, you wouldn't want
to try to grab the movie frames manu-
ally and display them in the content
field of the layer as this would create a lot of overhead, and your movie wouldn't play
smoothly. Instead, you would simply want to use a QTMovieLayer , which abstracts movie
playback very well. All you need to provide to a QTMovieLayer is a path to a movie file on
disk, and it handles the rest. Figure 1-1 shows the hierarchy of Core Animation layers and
the frameworks to which each of them belong.

NOTE

See Chapter 2, “What Can and Should I
Animate?,” to see a list of the animatable
properties of a layer.

QuartzCore.framework

CAAnimation
<CAAction, CAMediaTiming>
CAConstraint

NSObject CAAnimationGroup

CAPropertyAnimation
CATransition

CABasicAnimation
CAKeyframeAnimation

CALayer
<CAMediaTiming>

CAEAGLLayer*

CAScrollLayer

CAMediaTimingFunction
CATransaction

CATiledLayer
CAGradientLayer

CAShapeLayer

CAReplicatorLayer

CAConstraintLayoutManager CATextLayer **

CARenderer CAOpenGLLayer **

QuartzComposer.framework

QCCompositionLayer **

QTKit.framework

QTCaptureLayer **
QTMovieLayer **

**OS X only *iPhone OS only

FIGURE 1-1

Core Animation Layers

As Figure 1-1 shows, there are numerous layers available in the Core Animation toolbox.
Here is a brief explanation of each layer type:

. CALayer

This is the base class from which all Core Animation layers derive.