Changes with IOS 9

I was programming using the Objective-C language and when the Xcode 7 update was done, some errors appeared in the language, one of them is in the file AppDelegate.m :

(NSManagedObjectContext *)managedObjectContext {
    // Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.)
    if (_managedObjectContext != nil) {
        return _managedObjectContext;
    }

    NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
    if (!coordinator) {
        return nil;
    }

    _managedObjectContext = [[NSManagedObjectContext alloc] init];
    [_managedObjectContext setPersistentStoreCoordinator:coordinator];
    return _managedObjectContext;
}

For the highlighted line it displays the following error:

  

init is deprecated - Use initWithConcurrencyType: instead

How should I write this new structure instead of init ?