User Interaction - Core Animation - page 182

LISTING 11-5

Continued

- ( void )setString:( NSString *)string;
{

[ textLayer setString :string];
CGRect textRect;
textRect. size = [ textLayer preferredFrameSize ];
[ textLayer setBounds :textRect];

}

The -setSelected: method (as shown in Listing 11-6) provides visible feedback to the
user so that they can see the click has an effect on the application. To show this effect, we
add and remove a Core Image filter ( CIBloom ) to the button layer depending upon the
BOOL value being passed in.

LISTING 11-6

LZButton -setSelected: Implementation

- ( void )setSelected:( BOOL )selected
{

if (!selected) {
[ self setFilters : nil ];
return ;

}
CIFilter *effect = [ CIFilter filterWithName : @”CIBloom” ];
[effect setDefaults ];
[effect setValue : [ NSNumber numberWithFloat : 10.0f] forKey : @”inputRadius” ];
[effect setName : @”bloom” ];
[ self setFilters : [ NSArray arrayWithObject :effect]];

}

NOTE

Remember that Core Image filters are currently only available on the desktop. Therefore, the
filter changes in the -setSelected: method will not work on a Cocoa Touch device.

Interface Builder
With the LZButton layer designed, the next thing we build is the AppDelegate . The
AppDelegate contains all the layers; add them to the window's contentView and receive
the delegate calls.

The only thing we do in Interface Builder is change the window's contentView to an
instance of LZContentView . After the class type has been changed, bind the ContentView 's