R – What does it mean that a fetched property is static and not dynamically updating itself

To-one relationships are modeled as object references by Core Data. So a to-one relationship from Entity Bar to entity Baz (assuming Baz is implemented by the class Baz) would be

@interface Bar : NSManagedObject {
}

@property (readwrite,nonatomic) Baz * toBaz;

@end

To-many relationships are modeled as a mutable set property (though not as an NSMutableSet). Assuming a to-many relationship from Bar to Baz called manyBazz:

@interface Bar : NSManagedObject {

}

@property (retain) NSSet* manyBazz;

@end

// coalesce these into one @interface AnalysisRecord (CoreDataGeneratedAccessors) section
@interface Bar (CoreDataGeneratedAccessors)
- (void)addManyBazzObject:(Baz *)value;
- (void)removeManyBazzObject:(Baz *)value;
- (void)addManyBazz:(NSSet *)value;
- (void)removeManyBazz:(NSSet *)value;

@end

If you want to use the NSMutableSet interface to manipulate the manyBazz relationship, you should call -mutableSetValueForKey:@"manyBazz" to get a KVO-compliant proxy for the manyBazz relationship.

On Leopard (OS X 10.5) and later, all appropriate methods are automaticall generated at run-time by the Core Data framework, even if you do not explicitly declare or implement them (you will, of course, get a compiler warning if you try to use them without declaring them in a header file). Thus you do not need to subclass

The easiest way to get the declaration and implementation right is to select the attributes in the data modeler and choose "Copy Objective-C 2.0 Method Declarations To Clipboard" from the "Design->Data Model" menu, the paste into your implementing classes .h file. Of course, you have to keep your .h and model in sync... hence a hearty recommendation for rentzsch's awesome MO Generator, a tool that will automatically generate (and re-generate) NSManagedObject subclasses from your data model.

Have you tried using valueForKey: and passing in the name of your fetched property? That's how I would expect it to work. I would also expect that it would return an NSSet object, but that's easily verified by doing this:

id results = [myManagedObject valueForKey:@"fetchedPropertyName"];
NSLog(@"%@", [results className]);