从UITableView删除UITableViewCell

Question

I am using fmdb to manage some data that is display on a regular UITableView. I am attempting to delete one cell using this code:

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
    if (editingStyle == UITableViewCellEditingStyleDelete) {
        db = [FMDatabase databaseWithPath:[Utility getDatabasePath]];


        [db open];

        [db beginTransaction];

        NSString * stringtoInsert = [NSString stringWithFormat: @"DELETE FROM TTLogObject WHERE id='%@'", [idArray objectAtIndex:indexPath.row]];

        BOOL success = [db executeUpdate:stringtoInsert];

        if (!success)
        {
            NSLog(@"insert failed!!");
        }

        NSLog(@"Error %d: %@", [db lastErrorCode], [db lastErrorMessage]);

        [db commit];

        [db close];

        [self getList];
    }
}

Here is the code for viewDidLoad and the getList function that I am using.

   - (void)viewDidLoad
{
    [super viewDidLoad];

     self.navigationController.navigationBar.tintColor = [UIColor blackColor];

    shipperCityArray = [[NSMutableArray alloc] init];
    pickupDateArray = [[NSMutableArray alloc] init];
    paidArray = [[NSMutableArray alloc] init];
    idArray = [[NSMutableArray alloc] init];

    //NSString *path  = [[NSBundle mainBundle] pathForResource:@"tt" ofType:@"db"];


    [self getList];

}

- (void)getList
{
    db = [FMDatabase databaseWithPath:[Utility getDatabasePath]];
    [shipperCityArray removeAllObjects];
    [pickupDateArray removeAllObjects];
    [paidArray removeAllObjects];
    [idArray removeAllObjects];

    [db open];

    FMResultSet *fResult= [db executeQuery:@"SELECT * FROM TTLogObject"];


    while([fResult next])
    {
        [shipperCityArray addObject:[fResult stringForColumn:@"shipperCity"]];
        [pickupDateArray addObject:[fResult stringForColumn:@"pickupDate"]];
        [paidArray addObject:[NSNumber numberWithBool:[fResult boolForColumn:@"paid"]]];
        [idArray addObject:[NSNumber numberWithInteger:[fResult intForColumn:@"id"]]];
        NSLog(@"%@", [NSNumber numberWithInteger:[fResult intForColumn:@"id"]]);
    }


    [db close];

    [self.tableView reloadData];
}

The issue is that the data gets deleted just fine from the database. However, after delete is pressed, the table view does not display any cells anymore. When I restart the app, the proper data gets loaded again, with the cell that was deleted actually gone. I suspect it has something to do with numberOfRowsInSection .

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    NSLog(@"%i", [shipperCityArray count]);
    return [shipperCityArray count];
}

When the app is launched, it prints the proper amount of cells, but when delete is hit, it does not print anything, and seems to not be called.

I have attempted to use [self.tableView beginUpdates] and [self.tableView endUpdates] but those seem to error out stating something about the wrong number of items resulting after the delete. I am not sure how to solve this. If I must use beginUpdates and endUpdates, can someone explain to me how this should be done properly, and what is actually going on?

Answer 1

Instead of calling reloadData, you need to explicitly tell your tableView you are deleting a cell. Replace

[self.tableView reloadData];

with

[self.tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationLeft];

You should call this in your commitEditingStyle method.