Get full access to Cocoa Programming for Mac OS X, Third Edition and 60K+ other titles, with a free 10-day trial of O'Reilly.
There are also live events, courses curated by job role, and more.
Key-value coding (KVC) is a mechanism that allows you to set and get the value of a variable by its name. The name is simply a string, but we refer to that name as a key . So, for example, imagine that you have a class called Student that has an instance variable called firstName of type NSString :
@interface Student : NSObject < NSString *firstName; >. @ends
If you had an instance of Student , you could set its firstName like this:
Student *s = [[Student alloc] init]; [s setValue:@"Larry" forKey:@"firstName"];
You could read the value of its firstName like this:
NSString *x = [s valueForKey:@"firstName"];
The methods setValue:forKey: and valueForKey: are defined in NSObject . Even though this doesn’t .
Get Cocoa Programming for Mac OS X, Third Edition now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.