Implicit Animations - iOS Core Animation - page 155

from Listing 7.2 that removes the colorLayer and sets the layerView backing layer's
background color directly.
Listing 7.4 Setting the Property of the Backing Layer Directly
@interface ViewController ()
@property ( nonatomic , weak ) IBOutlet UIView *layerView;
@end
@implementation ViewController
- ( void )viewDidLoad
{
[ super viewDidLoad ];
//set the color of our layerView backing layer directly
self .layerView. layer . backgroundColor = [ UIColor blueColor ]. CGColor ;
}
- ( IBAction )changeColor
{
//begin a new transaction
[ CATransaction begin ];
//set the animation duration to 1 second
[ CATransaction setAnimationDuration : 1.0 ];
//randomize the layer background color
CGFloat red = arc4random () / ( CGFloat ) INT_MAX ;
CGFloat green = arc4random () / ( CGFloat ) INT_MAX ;
CGFloat blue = arc4random () / ( CGFloat ) INT_MAX ;
self .layerView. layer . backgroundColor = [ UIColor colorWithRed :red
green :green
blue :blue
alpha : 1.0 ]. CGColor ;
//commit the transaction
[ CATransaction commit ];
}