Initialising CoreData in AppleScript-objc - objective-c

Question

I'm trying to write and read from CoreData on OSX, combinig cocoa classes with applescript-objc.
I wrote methods to handle my CoreData as in tutorial (youtube, Cocoa Tutorial: Core Data Introduction in iOS and Mac OS Programming Part 2) <- those are cocoa classes in my project
I have a class called CoreDataHelper that defines methods to manipulate Core Data. Here are some of them:
+(NSManagedObjectContext *) managedObjectContext{
NSError*error;
[[NSFileManager defaultManager] createDirectoryAtPath:[CoreDataHelper directoryForDatabaseFilename] withIntermediateDirectories:YES attributes:nil error:&error];
if(error){
NSLog(#"%#", [error localizedDescription]);
return nil;
}
NSString* path = [NSString stringWithFormat:#"%#/%#",[CoreDataHelper directoryForDatabaseFilename],[CoreDataHelper databaseFilename]];
NSURL *url = [NSURL fileURLWithPath:path];
NSManagedObjectModel* managedModel = [NSManagedObjectModel mergedModelFromBundles:nil];
NSPersistentStoreCoordinator* storeCordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:managedModel];
if(![storeCordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:url options:nil error:&error]){
NSLog(#"%#",[error localizedDescription]);
return nil;
}
NSManagedObjectContext* managedObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
return managedObjectContext;
}
+(id)insertManagedObjectOfClass:(Class) aClass inManagedObjectContext:(NSManagedObjectContext *)managedObjectContext{
NSManagedObject* managedObject = [NSEntityDescription insertNewObjectForEntityForName:NSStringFromClass(aClass) inManagedObjectContext:managedObjectContext];
return managedObject;
}
I'm using .xcdatamodeld for my Model.
I have 2 entities in it with classes for each one of them:
Tab
Service
Tab.h looks like this
#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>
#class Service;
NS_ASSUME_NONNULL_BEGIN
#interface Tab : NSManagedObject
// Insert code here to declare functionality of your managed object subclass
#end
NS_ASSUME_NONNULL_END
#import "Tab+CoreDataProperties.h"
and Tab.m looks like this:
#import "Tab.h"
#import "Service.h"
#implementation Tab
// Insert code here to add functionality to your managed object subclass
#end
Tab+CoreDataProperties.h:
#import "Tab.h"
NS_ASSUME_NONNULL_BEGIN
#interface Tab (CoreDataProperties)
#property (nullable, nonatomic, retain) NSString *nZakladka;
#property (nullable, nonatomic, retain) NSString *uZakladka;
#property (nullable, nonatomic, retain) Service *podstronaSerwisu;
#end
NS_ASSUME_NONNULL_END
Tab+CoreDataProperties.m:
#import "Tab+CoreDataProperties.h"
#implementation Tab (CoreDataProperties)
#dynamic nZakladka;
#dynamic uZakladka;
#dynamic podstronaSerwisu;
#end
Now, my AppDelegate.applescript looks like this
...
property CoreDataHelper: class "CoreDataHelper"
property cService: class "Service"
property cTab: class "Tab"
script AppDelegate
on applicationWillFinishLaunching_(aNotification)
set theContext to CoreDataHelper's managedObjectContext()
set ccTab to cTab's alloc()'s init()
//the one below cause an error "CoreData: error: Failed to call designated initializer on NSManagedObject class 'Tab'"
set theTab to CoreDataHelper's insertManagedObjectOfClass_inManagedObjectContext_(ccTab, theContext)
end applicationWillFinishLaunching_
...
end Script
When I run whole thing I got an error message posted in a commented line in AppleScriptObjC code. The method that is causing an error is NSManagedObject* managedObject = [NSEntityDescription insertNewObjectForEntityForName:NSStringFromClass(aClass) inManagedObjectContext:managedObjectContext];
What is the problem?