NSMutableArray KVC/KVO question - objective-c

Question

This is a sample from book "Cocoa Programming For Mac Os X 3rd(HD)" chapter 7 "Key-Value Coding. Key-Vaule Observing
Here is the code:
Person.h:
#import <Foundation/Foundation.h>
#interface Person : NSObject {
NSString *personName;
float expectedRaise;
}
#property (readwrite, copy) NSString *personName;
#property (readwrite) float expectedRaise;
#end
Person.mm:
#import "Person.h"
#implementation Person
#synthesize expectedRaise;
#synthesize personName;
- (id)init
{
[super init];
expectedRaise = 0.05;
personName = #"New Person";
return self;
}
- (void)dealloc
{
[personName release];
[super dealloc];
}
#end
MyDocument.h:
#import <Cocoa/Cocoa.h>
#interface MyDocument : NSDocument
{
NSMutableArray *employees;
}
#property (retain) NSMutableArray *employees;
#end
MyDocument.mm:
#import "MyDocument.h"
#import "Person.h"
#implementation MyDocument
#synthesize employees;
- (id)init
{
if (![super init])
return nil;
employees = [[NSMutableArray alloc] init];
return self;
}
- (void)dealloc
{
[employees release];
[super dealloc];
}
- (void)windowControllerDidLoadNib:(NSWindowController *) aController
#end
And the sample works fine.(A blank table at first and you can add or delete record).
Now I tried to add some records to the array so that the blank table would have
someting in it at first.
Here's what I'v tried(inside the init method):
[self willChangeValueForKey:#"employees"];
Person *p1 = [[Person alloc] init];
[employees addObject: [NSData dataWithBytes: &p1 length: sizeof(p1)]];
[self didChangeValueForKey:#"employees"];
But when I build and wrong I got the error msg:
[<NSConcreteData 0x422bf0> valueForUndefinedKey:]: this class is not key value coding-compliant for the key personName.
......
Can any one help me out of here? Thanks in advance ^_^

Answer 1

That seems like a very reasonable response... you added NSData to your array named employees; guessing from the names, and from the KVC, you probably meant to add p1 to your array instead. So, try:
[employees addObject:p1];