重新排列TableView时如何更改CoreData的索引？

Question

Please go through the code and tell me what i am doing wrong here.

TableViewController.m

-(void)viewDidAppear:(BOOL)animated{

    [super viewDidAppear:animated];
    NSManagedObjectContext *context = [self managedObjectContext];
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Device" inManagedObjectContext:context];

    NSFetchRequest *fetchrequest = [[NSFetchRequest alloc]initWithEntityName:entity];
    _devices = [[context executeFetchRequest:fetchrequest error:nil]mutableCopy];
    [self.tableView reloadData]; // When TableView is reloading the data in tableview updating according to the data stored via CoreData.

}


- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath {

    if (fromIndexPath != toIndexPath ) {

        NSManagedObjectContext *context = [self managedObjectContext];
        NSManagedObject *device = [self.devices objectAtIndex:fromIndexPath.row];

        NSString *str1 = [device valueForKey:@"text1"];

        NSLog(@"%@",str1);
        [self.devices removeObject:device];

        [self.devices insertObject:device atIndex:[toIndexPath row]];

//        int i = 0;
//        for (NSManagedObject *mo in self.devices)
//        {
//            NSManagedObject *new = [self.devices objectAtIndex:i];
//            NSString *check = [new valueForKey:@"text1"];
//            NSLog(@"%@",check);
//            NSString *check1 = [new valueForKey:@"text2"];
//            NSLog(@"%@",check1);
//            NSString *check2 = [new valueForKey:@"text3"];
//            NSLog(@"%@",check2);
//            [mo setValue:[NSString stringWithFormat:@"%@",[new valueForKey:@"text1"]] forKey:@"text1"];
//            [mo setValue:[NSString stringWithFormat:@"%@",[new valueForKey:@"text2"]] forKey:@"text2"];
//            [mo setValue:[NSString stringWithFormat:@"%@",[new valueForKey:@"text3"]] forKey:@"text3"];
//            i++;
//        }


        NSError *error;

        if(![context save:&error]){
            NSLog(@"%@ %@",error, [error localizedDescription]);
        }

    }

}

I have entity Name: Device and with column names: text1,text2,text3

I don't want to sort the data in Core Data, actually i want to move the rows in TableView and i want to update the index of the data saved in columns text1,text2,text3. In total, there are 5 rows in tableview and i just want to update the index of the values with respect to the tableview index which is updated.

Answer 1

Check below tutorial

http://www.cimgf.com/2010/06/05/re-ordering-nsfetchedresultscontroller/

for short you need to add "displayIndex" property to the objects you are trying to reoder