相关数据保存Coredata

Question

I am trying save a data into core data. ( Main model and related model). When I save after kill main model is saved but doesn't related model saved. I have a following code:

NSManagedObjectContext *context = [self managedObjectContext];


    Trace *trace = [NSEntityDescription
                    insertNewObjectForEntityForName:@"Trace"
                    inManagedObjectContext:context];


    trace.totalDistance = self.totalDistance;
    trace.averageSpeed = self.averageSpeed;
    trace.theBestSpeed = self.theBestSpeed;
    trace.stopTime = [NSNumber numberWithInt: self.stopTime];
    trace.time = self.time;
    NSMutableArray *nsa = [[NSMutableArray alloc] init];
     for (int i=0;i<locations.count;i++){
     CLLocation* cl =(CLLocation*) locations[i];
         Argument *point = [NSEntityDescription
                            insertNewObjectForEntityForName:@"Argument"
                            inManagedObjectContext:context];

     point.latitude = [NSNumber numberWithDouble:  cl.coordinate.latitude];
     point.langitude = [NSNumber numberWithDouble:  cl.coordinate.longitude];
     point.speed = self.speeds[i];
     [nsa addObject:point];
     }
    NSOrderedSet * ns = [[NSOrderedSet alloc] initWithArray:nsa];
    trace.points = ns;


    NSError *error;
    if (![context save:&error]) {
        NSLog(@"Whoops, couldn't save: %@", [error localizedDescription]);
    }

When I kill an application Arguments don't saved , but Trace is saved. Shat can cause the problem??

Answer 1

Quite simply, when you kill the app before it saves, it doesn't save. No surprises.

Answer 2

First - make sure you're using entity relationships the correct way.

In xcode model editor select your entity, go down to Relationships and make sure you have a 'To-Many' relationship to your Argument object. Don't use attribute to link your objects, that won't work.

After doing that (you can check the images below) you associate new objects the the 'Trace' object using [traceObject addArgumentsObject:argument] and remove them the same way.

For further check the Core Data Programming guide

Model -

Property of the relationship -

Aft