@property and @synthesize

Question

Hi there : )
I bought the third edition of the Aaron Hilleglass book 'Cocoa Programming For MacOSX'.
In an application, the author uses the @property/@synthesize keywords instead of implementing accessors in a traditional way. The application illustrates the NSArrayController. The code can be found here : http://www.2shared.com/file/5756321/ce291cd9/RaiseMan.html
But when I implement this code, I get a strange behavior. This application uses a NSTableView to store some objects (person for instance with the person's name and an associated float value). When I change the value of a Cell and I use press "Enter" or "Tab" key, the application crashes.
Here is the strange thing : if I implement accessors the old way, by redefining a set and a get method, the crash is gone. It perfectly works... (the code above is the one where I implemented the accessors. The @property/@synthetize were commented)
Since a new release of XCode was made since the book was published, I wondered if something has changed that could cause the crash. I already contacted the author, but I don't get any answers, so I give it a shot here.
Thanks.

Answer 1

oki doki, I didnt knew the code in brackets. I tried the BBS [code] but it did not work : )
So, here's the Person's Code (h & m in the same code section) :
#import <Foundation/Foundation.h>
@interface Person : NSObject {
NSString* personName;
float expectedRaise;
@property(readwrite, assign) NSString* personName;
@property(readwrite) float expectedRaise;
/-(void)setPersonName:(NSString)name;
-(void)setExpectedRaise:(float)amount;
-(NSString*)personName;
-(float)expectedRaise; */
@end
#import "Person.h"
@implementation Person
// SET et GET
//@synthesize personName;
//@synthesize expectedRaise;
-(id)init
if (![super init])
return nil;
personName = @"Nouvelle Personne";
expectedRaise = 0.5;
return self;
-(void)dealloc
[personName release];
[super dealloc];
@end
Here is the MyDocument code :
#import <Cocoa/Cocoa.h>
@interface MyDocument : NSDocument
NSMutableArray* employees;
-(void)setEmployees:(NSMutableArray*)a;
@end
#import "MyDocument.h"
@implementation MyDocument
- (id)init
self = [super init];
if (self) {
employees = [[NSMutableArray alloc]init];
// Add your subclass-specific initialization here.
// If an error occurs here, send a [self release] message and return nil.
return self;
-(void)dealloc
[self setEmployees:nil];
[super dealloc];
- (NSString *)windowNibName
// Override returning the nib file name of the document
// If you need to use a subclass of NSWindowController or if your document supports multiple NSWindowControllers, you should remove this method and override -makeWindowControllers instead.
return @"MyDocument";
- (void)windowControllerDidLoadNib:(NSWindowController *) aController
[super windowControllerDidLoadNib:aController];
// Add any code here that needs to be executed once the windowController has loaded the document's window.
- (NSData *)dataOfType:(NSString *)typeName error:(NSError **)outError
// Insert code here to write your document to data of the specified type. If the given outError != NULL, ensure that you set *outError when returning nil.
// You can also choose to override -fileWrapperOfType:error:, -writeToURL:ofType:error:, or -writeToURL:ofType:forSaveOperation:originalContentsURL:error: instead.
// For applications targeted for Panther or earlier systems, you should use the deprecated API -dataRepresentationOfType:. In this case you can also choose to override -fileWrapperRepresentationOfType: or -writeToFile:ofType: instead.
if ( outError != NULL ) {
*outError = [NSError errorWithDomain:NSOSStatusErrorDomain code:unimpErr userInfo:NULL];
return nil;
- (BOOL)readFromData:(NSData *)data ofType:(NSString *)typeName error:(NSError **)outError
// Insert code here to read your document from the given data of the specified type. If the given outError != NULL, ensure that you set *outError when returning NO.
// You can also choose to override -readFromFileWrapper:ofType:error: or -readFromURL:ofType:error: instead.
// For applications targeted for Panther or earlier systems, you should use the deprecated API -loadDataRepresentation:ofType. In this case you can also choose to override -readFromFile:ofType: or -loadFileWrapperRepresentation:ofType: instead.
if ( outError != NULL ) {
*outError = [NSError errorWithDomain:NSOSStatusErrorDomain code:unimpErr userInfo:NULL];
return YES;
-(void)setEmployees:(NSMutableArray*)a
if (a == employees)
return;
[a retain];
[employees release];
employees = a;
@end
I don't know how to show you the xib file since it's a bit long...
Nothing particular about this code. I really think it comes from the NSArrayController or sometinhg.
Moreover, if I use the author's code, it actually bugs if I remember it well....