Key-Value Coding, Key-Value observing(Chapter 7 of Cocoa Programming for Mac OS X)

1 #import <Foundation/Foundation.h>

2

3

4 @interface AppController : NSObject

5 {

6 int fido;

7 }

8

9 - (int)fido;

- (void)setFido:(int)x;

- (IBAction)incrementFido:(id)sender;

@end

AppController.m 1 #import "AppController.h"
2
3 @implementation AppController
4
5 - (id)init
6 {
7 [super init];
8 [self setValue:[NSNumber numberWithInt:5] forKey:@"fido"];
9 NSNumber *n = [self valueForKey:@"fido"];
NSLog(@"fido = %@", n);
return self;
}

- (int)fido
{
NSLog(@"-fido is returning %d", fido);
return fido;
}

- (void)setFido:(int)x
{
NSLog(@"-setFido: is called with %d", x);
fido = x;
}

- (IBAction)incrementFido:(id)sender
{
[self willChangeValueForKey:@"fido"];
fido++;
NSLog(@"fido is now %d", fido);
[self didChangeValueForKey:@"fido"];
}

@end