The Layer Tree - iOS Core Animation - page 8

target's Build Phases tab (see Figure 1.4), and then import
<QuartzCore/QuartzCore.h> in the view controller's .m file.
Figure 1.4 Adding the QuartzCore framework to the project
After doing that, we can directly reference CALayer and its properties and methods in our
code. In Listing 1.1, we create a new CALayer programmatically, set its
backgroundColor property, and then add it as a sublayer to the layerView backing
layer. (The code assumes that we created the view using Interface Builder and that we have
already linked up the layerView outlet.) Figure 1.5 shows the result.
The CALayer backgroundColor property is of type CGColorRef , not UIColor
like the UIView class's backgroundColor , so we need to use the CGColor property
of our UIColor object when setting the color. You can create a CGColor directly using
Core Graphics methods if you prefer, but using UIColor saves you from having to
manually release the color when you no longer need it.
Listing 1.1 Adding a Blue Sublayer to the View
#import "ViewController.h"
#import <QuartzCore/QuartzCore.h>
@interface ViewController ()
@property ( nonatomic , weak ) IBOutlet UIView *layerView;