Redraw UITableViewCell After Draw

I'm adding 'pull to load more' to a UITableView. I've got the reloading working and I can add more data, but I'm trying to display a UIActivityIndicatorView when the data loads. I've managed to get the current accessory to disappear, but I can't make the actitity indicator draw itself.

This is the code I have in my UITableViewCell subclass:

-(void) toggleLoading:(bool)showLoading {
    if(showLoading) {
        [self.accessoryView setHidden:true];
        isLoading = false;
    } else {
        UIActivityIndicatorView *spinner = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
        spinner.frame = CGRectMake(0, 0, 24, 24);
        self.accessoryView = spinner;
        [spinner startAnimating];
        [spinner release];
        isLoading = true;
        [self.backgroundView setNeedsDisplay];
    }
}

The method is called and when the data finishes loading, the correct accessory is shown aga开发者_JAVA百科in. Is there an extra step I need?

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Shouldn't you be drawing the spinner in didSelectRowAtIndexPath?

btw I would use:

[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;

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Turned out I was trying to call this from a separate thread (using GCD), hence the lag in updating the UI. The solution was to move the UI calls onto the UI thread.