Question

I’m trying to reload my app with new data from a JSON feed. i’d try;

- (void) Refresh {
[self performSelector:(@selector(refreshDisplay:)) withObject:(_tableView) afterDelay:0.5];
}

and

- (void)refreshDisplay:(UITableView *)tableView {

    [_tableView reloadData]; 
}

Downloading the JSON:

     NSString *jsonString = [NSString 
                                stringWithContentsOfURL:[NSURL URLWithString:xmlDataUrl] 
                                encoding:NSUTF8StringEncoding
                                error:nil];

        SBJSON *parser = [[SBJSON alloc] init];
        NSDictionary *results = [parser objectWithString:jsonString error:nil];

        parser = nil;

        [self setTableData:nil];
        [self setTableData:[results objectForKey:@"feed"]];

But it’s not reloading my new data from the JSON, does anyone know how i can update the tableview with new data i’m downloading from a online JSON feed? I need to delete the old data from the JSON feed and insert the new data.

Answer 1

Are you sure your data is actually changing? You could place some NSLogs in your -tableView:cellForRowAtIndexPath: method to make sure it’s getting called. It seems like your issue is that you’re simply telling it to refresh after half a second, and the data may not be loaded by then. I suggest you put the [tableView reloadData] call in the method which actually finishes updating the data, so that you know it’s done by the time you call it.

Note too that this method:

- (void)refreshDisplay:(UITableView *)tableView {
    [_tableView reloadData]; 
}

isn’t needed. First of all, it ignores the argument and calls reloadData on your ivar _tableView. Secondly, if all you wanted to do was reload the data after half a second, you can call:

[_tableView performSelector:@selector(reloadData) withObject:nil afterDelay:.5];

Further, based on the fact that it’s called _tableView if you have an @synthesize tableView=_tableView you’re better off using self.tableView anywhere you can, as this avoids accessing the ivar directly and is considered “good form”.

To reiterate, make sure your data source is actually updating the data before calling reloadData on the tableview.

Edit

To your updated post, simply add [self.tableView reloadData]; at the end of your JSON parsing code.