Question

Helo, I’m still newbie with Core Data and suddenly stuck in these simple code:

Purchased* newItem=[NSEntityDescription insertNewObjectForEntityForName:@"Purchased" inManagedObjectContext:self.managedObjectContext];
[newItem setPurchasedDate:[NSDate date]];
[newItem setLastOpen:[NSDate date]];
if ([self.managedObjectContext save:&error])
{
   //do something if the save success
}

Well, from the code above I’ve Got an ‘NSInvalidArgumentException’, reason: ‘-[Purchased setPurchasedDate:]: unrecognized selector sent to instance. As we can see the exception is pointing at

[newItem setPurchasedDate:[NSDate date]];

and that is right. When I try to debug this code step by step, the program just abort when this message is invoked.

I wonder why, cause there is no wrong in my model and my Purchased class, I’ve checked it hundred times. I have tried to change the location of setting value by overwrite -(void)awakeFromInsert() method and it’s fire the same exception. Is anyone has a suggestion? thanks before.

Answer 1

Check this:

Your managed object model’s Purchased entity has an attribute of type Date that is called purchasedDate, and another one called lastOpen.

In your Purchased.h file you have

@property (nonatomic, strong) NSDate *purchasedDate;
@property (nonatomic, strong) NSDate *lastOpen;

In your Purchased.mfile you have

@dynamic purchasedDate;
@dynamic lastOpen;

Make sure you #import "Purchased.h" in the file where you create the new instance.