Core Data operations(insert , delete , select) and also get Last inserted id :

Select All data from an entity  in Core Data :

-(NSArray *)selectAllData:(NSString *)entityName{

    AppDelegate  *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];

    NSManagedObjectContext *context = [appDelegate managedObjectContext];

    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];

    NSEntityDescription *entity = [NSEntityDescription entityForName:entityName inManagedObjectContext:context];

    [fetchRequest setEntity:entity];

    return [context executeFetchRequest:fetchRequest error:nil];

}

Select Data from an entity in core Data with condition :

-(NSArray *)selectConData:(NSString *)entityName dataForCon:(NSMutableDictionary *)dataForCon id_entity:(int)id_e{

    AppDelegate  *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];

    NSManagedObjectContext *context = [appDelegate managedObjectContext];

    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];

    NSEntityDescription *entity = [NSEntityDescription entityForName:entityName inManagedObjectContext:context];

    [fetchRequest setEntity:entity];

    NSArray *arrAllKey=[dataForCon allKeys];

    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"user_id=%d",id_e];

    [fetchRequest setPredicate:predicate];

    return [context executeFetchRequest:fetchRequest error:nil];

    

}

Insert Data in entity : 

-(BOOL)insertData:(NSString *)entityName dataForInsert:(NSMutableDictionary *)dataForInsert{

    AppDelegate  *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];

    NSManagedObjectContext *context = [appDelegate managedObjectContext];

    NSManagedObject *newContact;

    newContact = [NSEntityDescription

                  insertNewObjectForEntityForName:entityName

                  inManagedObjectContext:context];

    NSArray*keys=[dataForInsert allKeys];

    for(int i=0;i<keys.count;i++){

        [newContact setValue:[dataForInsert valueForKey:(NSString *)[keys objectAtIndex:i]] forKey:[keys objectAtIndex:i]];

    }

    

    NSError *error;

    if([context save:&error]){

        return true;

    }else{

        return false;

    }

}

Get Last inserted id in Particular Entity :

-(NSArray *)getLastId:(NSString *)entityName idForTable:(NSString *)key{

    NSSortDescriptor *sort = [[NSSortDescriptor alloc] initWithKey:key ascending:NO];

    NSArray *sortDescriptors = [NSArray arrayWithObject:sort];

    AppDelegate  *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];

    NSManagedObjectContext *context = [appDelegate managedObjectContext];

    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];

   [fetchRequest setSortDescriptors:sortDescriptors];

    NSEntityDescription *entity = [NSEntityDescription entityForName:entityName inManagedObjectContext:context];

    [fetchRequest setEntity:entity];

    return[context executeFetchRequest:fetchRequest error:nil];

}

Delete All data from an entity :

-(BOOL)deleteAllData:(NSString *)entityName{

    NSMutableArray *objAll= (NSMutableArray *)[self selectAllData:entityName];

    AppDelegate  *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];

    for(int i=0;i<objAll.count;i++){

        NSManagedObjectContext *context = [appDelegate managedObjectContext];

        User_info *obj=[objAll objectAtIndex:i];

        [context deleteObject:obj];

        [context save:nil];

    }

    return YES;

}