Specialized Layers - iOS Core Animation - page 105

CATextLayer also renders much faster than UILabel . It's a little-known fact that on
iOS6 and earlier, UILabel actually uses WebKit to do its text drawing, which carries a
significant performance overhead when you are drawing a lot of text. CATextLayer uses
Core Text and is significantly faster.
Let's try displaying some text using a CATextLayer . Listing 6.2 shows the code to set up
and display a CATextLayer , and Figure 6.2 shows the result.
Listing 6.2 Implementing a Text Label Using CATextLayer
@interface ViewController ()
@property ( nonatomic , weak ) IBOutlet UIView *labelView;
@end
@implementation ViewController
- ( void )viewDidLoad
{
[ super viewDidLoad ];
//create a text layer
CATextLayer *textLayer = [ CATextLayer layer ];
textLayer. frame = self .labelView. bounds ;
[ self .labelView. layer addSublayer :textLayer];
//set text attributes
textLayer. foregroundColor = [ UIColor blackColor ]. CGColor ;
textLayer. alignmentMode = kCAAlignmentJustified ;
textLayer. wrapped = YES ;
//choose a font
UIFont *font = [ UIFont systemFontOfSize : 15 ];
//set layer font
CFStringRef fontName = ( __bridge CFStringRef )font. fontName ;
CGFontRef fontRef = CGFontCreateWithFontName (fontName);
textLayer. font = fontRef;
textLayer. fontSize = font. pointSize ;
CGFontRelease (fontRef);
//choose some text
NSString *text = @"Lorem ipsum dolor sit amet, consectetur adipiscing \
elit. Quisque massa arcu, eleifend vel varius in, facilisis pulvinar \
leo. Nunc quis nunc at mauris pharetra condimentum ut ac neque. Nunc \