property as NSManagedObject in view controller for a "current NSManagedObject" - objective-c

Question

I am interested in setting a property as a subclass, say Person, of NSManagedObject in a view controller that will specify an instance of person so that I will be able to update with methods in the controller. can I do it like this?
// Viewcontroller.h
#implementation
#property (nonatomic, retain) Person* currentPerson;
#end
// ViewController.m
#implementation
#dynamic currentPerson;
-(void) doSomethingToCurrentPerson {
currentPerson.SomeAtrribute=somevalue;
}
#end
It seems like if this were not a valid way to go, it would also be possible to set a unique identifier and then store CurrentPersonUniqueID as a property and use KVC. Is there a way to get something along the lines of what I posted to work, or am I better off with something closer to the KVC approach, or something totally different?

Answer 1

This code won't work until you replace #dynamic by #synthesize. #dynamic tells the compiler that -setCurrentPerson: and -currentPerson are implemented somewhere else, which is not the case.
So #synthesize currentPerson will create the currentPerson's getter/setter automatically. It won't have anything to do with the fact that Person is a NSManagedObject.
Also, either you can't access to currentPerson directly with this name, you have to use its getter:
self.currentPerson.attribute = something;
// or
[self currentPerson].attribute = something;
Correct code:
// Viewcontroller.h
#implementation
#property (nonatomic, retain) Person* currentPerson;
#end
// ViewController.m
#implementation
#synthesize currentPerson;
-(void) doSomethingToCurrentPerson {
self.currentPerson.SomeAtrribute = somevalue;
}
#end