Custom NSMangedObject accessor crashed NSOutlineView - cocoa

Question

I am thinking this is a bug in Core Data but before I file a bug report, I want to be sure it is not just me being stupid.
I set up an NSOutlineView to access the data of 5 different Core Data entities. Each entity's data is accessed with a different NSArrayController which is bound to the Entity and its' ManagedObjectContext. I then have the NSOutlineViewDataSource methods return the correct NSString object depending on which entity was expanded.
NOTE: entities is declared elsewhere as an NSArray with names for the entities.
- (id)outlineView:(NSOutlineView *)outlineView child:(NSInteger)index
ofItem:(id)item {
if(nil == item) {
return [entities objectAtIndex:index];
}
NSInteger entityIdx = [entities indexOfObject:item];
if (entityIdx == NSNotFound) {
return #"";
}
id returnObject = #"";
switch (entityIdx) {
case 0: {
Person *person = [[peopleArrayController arrangedObjects] objectAtIndex:index];
returnObject = person.fullName;
break;
}
case 1: {
Media *media = [[mediaArrayController arrangedObjects] objectAtIndex:index];
returnObject = media.imageTitle;
break;
}
case 2: {
Note *note = [[notesArrayController arrangedObjects] objectAtIndex:index];
returnObject = note.noteDescription;
break;
}
case 3: {
Source *source = [[sourcesArrayController arrangedObjects] objectAtIndex:index];
returnObject = source.title;
break;
}
case 4: {
Repository *repo = [[repostioriesArrayController arrangedObjects] objectAtIndex:index];
returnObject = repo.name;
break;
}
default:
break;
}
return returnObject;
}
The Person entity property fullName and the Media entity property imageTitle are custom accessors.
- (NSString *)fullName {
[self willAccessValueForKey:#"surName"];
[self willAccessValueForKey:#"givenName"];
NSString *firstName = [self valueForKey:#"givenName"];
NSString *lastName = [self valueForKey:#"surName"];
NSString *string = [NSString stringWithFormat:#"%# %#", (firstName) ? firstName : #"", (lastName) ? lastName : #""];
[self didAccessValueForKey:#"surName"];
[self didAccessValueForKey:#"givenName"];
return string;
}
- (id) imageTitle {
[self willAccessValueForKey:#"path"];
id title = [[self valueForKey:#"path"] lastPathComponent];
[self didAccessValueForKey:#"path"];
return title;
}
The program was crashing when I tried to expand the Person or the Media entities but not when I expanded the other entities. I traced the crash to [NSCell _setContents:][NSObject(NSObject) doesNotRecognizeSelector:]
I changed the Media property being returned to a standard Core Data accessor property #"path" and the program stopped crashing when I expanded the Media entity. So the problem is definitely related to the custom accessor.
FYI - I checked to make sure the entity was set to use the NSManagedObject class.
Can anyone give me a reason for the crash other than a bug?

Answer 1

I got around this problem by changing the method
- (id)outlineView:(NSOutlineView *)outlineView child:(NSInteger)index ofItem:(id)item
to return the managed object
case 1: {
Media *media = [[mediaArrayController arrangedObjects] objectAtIndex:index];
returnObject = media;
break;
}
Then I have the method
- (id)outlineView:(NSOutlineView *)outlineView objectValueForTableColumn:(NSTableColumn *)tableColumn byItem:(id)item
return the String
if ([item isKindOfClass:[Media class]]) {
Media *media = (Media *)item;
return media.imageTitle;
}