Generating a Core Data Model from code

gistfile1.m

- (void)generateModel {
    NSManagedObjectModel *model = [NSManagedObjectModel new];
    NSEntityDescription *runEntity = [NSEntityDescription new];
    runEntity.name = @"Run";
    runEntity.managedObjectClassName = @"Run";
    model.entities = @[runEntity];

    NSMutableArray *runProperties = [NSMutableArray new];

    NSAttributeDescription *dateAttribute = [NSAttributeDescription new];
    dateAttribute.name = @"date";
    dateAttribute.attributeType = NSDateAttributeType;
    dateAttribute.optional = NO;
    [runProperties addObject:dateAttribute];

    NSAttributeDescription *idAttribute= [NSAttributeDescription new];
    idAttribute.name = @"processID";
    idAttribute.attributeType = NSInteger32AttributeType;
    idAttribute.optional = NO;
    idAttribute.defaultValue = @0;
    [runProperties addObject:idAttribute];

    NSPredicate *validationPredicate = [NSPredicate predicateWithFormat:@"SELF >= 0"];
    NSString *validationWarning = @"Process ID < 0";
    [idAttribute setValidationPredicates:@[validationPredicate]
                  withValidationWarnings:@[validationWarning]];

    runEntity.properties = runProperties;

    NSDictionary *localizationDictionary = @{@"Property/processID/Entity/Run" : @"Process ID",
                                             @"Property/date/Entity/Run" : @"Date",
                                             @"ErrorString/Process ID < 0" : @"Process ID must not be less than 0"};
    model.localizationDictionary = localizationDictionary;
}