How can swap Row at fromIndex to toIndex in UITableView?

Question

I created simple project with ARC, in which I have UITableView. And I have NSMutableArray of NSMutableDictionary.

like

(
        {
        comment = "";
        "field_name" = "field_name 1";
        "main_id" = 1;
        "order_index" = 0;
        "picker_value" = "";
    },
        {
        comment = "";
        "field_name" = "field_name 2";
        "main_id" = 2;
        "order_index" = 1;
        "picker_value" = "";
    },
        {
        comment = "";
        "field_name" = "field_name 3";
        "main_id" = 3;
        "order_index" = 2;
        "picker_value" = "";
    },
        {
        comment = "";
        "field_name" = "field_name 4";
        "main_id" = 4;
        "order_index" = 3;
        "picker_value" = "";
    },
)

Value of key "field_name" is displayed on each Cell of my UITableView. It is working properly. But I want to put swap functionality on my UITableViewCell.

For Example:

1 value - 0 order_index 
2 value - 1 order_index -----
3 value - 2 order_index      |-> I Want to swap value 2 to 4…(But do not want to change order_index)
4 value - 3 order_index -----

It should Be

1 value - 0 order_index 
4 value - 1 order_index 
3 value - 2 order_index      
2 value - 3 order_index 

value of dictionary will swap but do not  want to change order_index

I know about methods of UITableView

- (BOOL)tableView:(UITableView *)tableView canMoveRowAtIndexPath:(NSIndexPath *)indexPath
{
    if(indexPath.row > self.MyArray.count-1)
        return NO;
    return YES;
}

// Process the row move. This means updating the data model to correct the item indices.
- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath
      toIndexPath:(NSIndexPath *)toIndexPath
{
    // here i get fromIndexPath.row and toIndexPath.row
    NSMutableDictionary *oldDict = [NSMutableDictionary dictionary];
    oldDict = [(NSMutableDictionary *)[self.listOfReportField objectAtIndex:fromIndexPath.row] copy];

    [self.myArray removeObject:oldDict];
    [self.myArray insertObject:[self.myArray objectAtIndex:toIndexPath.row-1] atIndex:fromIndexPath.row];
    [self.myArray insertObject:oldDict atIndex:toIndexPath.row];

    // Here i am not swap my row , what should be i need to do here ??
 }

b As my Requirement first I want to swap value of dictionary but not order_index here. I am not able to swap value.

Please give me suggestion.

Thanks in advance.

Answer 1

Step 1: Save the order index value as well it actual index (1st in your case) i.e. "order_index" = 1; and 4th one also.

Step 2: Swap(2nd value with 4th value).

Step 3: As it is array, replace the index value to the actual index(1st) and same for 4th.

EDIT: the full working code:

-(void)swapArray:(NSMutableArray *)array MaintaingOrderFrom:(NSInteger)swapFrom swapTo:(NSInteger)swapTo{
    [array exchangeObjectAtIndex:swapFrom withObjectAtIndex:swapTo];
    NSString *tempOrderIndex=array[swapFrom][@"order_index"];
    array[swapFrom][@"order_index"]=array[swapTo][@"order_index"];
    array[swapTo][@"order_index"]=tempOrderIndex;
}

Note: The array and dictionary inside should be Mutable.

EDIT 2: To check, I need to create your data model

NSMutableDictionary *dict1=[NSMutableDictionary dictionaryWithDictionary:@{@"comment": @"",
                     @"field_name":@"field_name 1",
                     @"main_id":@"1",
                     @"order_index":@"0",
                     @"picker_value":@""
                     }];
NSMutableDictionary *dict2=[NSMutableDictionary dictionaryWithDictionary:@{@"comment": @"",
                      @"field_name":@"field_name 2",
                      @"main_id":@"2",
                      @"order_index":@"1",
                      @"picker_value":@""
                      }];
NSMutableDictionary *dict3=[NSMutableDictionary dictionaryWithDictionary:@{@"comment": @"",
                      @"field_name":@"field_name 3",
                      @"main_id":@"3",
                      @"order_index":@"2",
                      @"picker_value":@""
                      }];
NSMutableDictionary *dict4=[NSMutableDictionary dictionaryWithDictionary:@{@"comment": @"",
                      @"field_name":@"field_name 4",
                      @"main_id":@"4",
                      @"order_index":@"3",
                      @"picker_value":@""
                      }];

NSMutableArray *array=[NSMutableArray arrayWithArray:@[dict1,dict2,dict3,dict4]];

[self swapArray:array MaintaingOrderFrom:1 swapTo:3];

NSLog(@"%@",array);

Answer 2

NSMutableArray has a method - (void)exchangeObjectAtIndex:(NSUInteger)idx1 withObjectAtIndex:(NSUInteger)idx2 Why not call that method using your two values fromIndexPath and toIndexPath?

If I'm reading your question correctly, you want the "order_index" K/V pair in the dictionary to match that of the order of the array? After you've swapped the values using the method above, you could just call:

[[self.myArray objectAtIndex:fromIndexPath.row] setObject:[NSNumber numberWithInt:fromIndexPath.row] forKey:@"order_index"];
[[self.myArray objectAtIndex:toIndexPath.row] setObject:[NSNumber numberWithInt:toIndexPath.row] forKey:@"order_index"];