UITableView is only populated after I scroll - ios

Question

I have 2 table views in 2 view controllers. When i select a cell from first screen i want to load the second table , but my problem is : the table is empty and is populating after i scroll.
This is how i populate my table :
When cell is selected :
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
NSURL *url = [NSURL URLWithString:#"http://privatereisen.com/"];
ProgViewController *cd = [self.storyboard instantiateViewControllerWithIdentifier:#"progidentifview"];
AFHTTPClient *httpClient = [[AFHTTPClient alloc] initWithBaseURL:url];
NSString *path=[NSString stringWithFormat :#"dok/TV/pays/italie/json/chaine%d.json",indexPath.row];
[httpClient postPath:path parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject)
{resultofData = [NSJSONSerialization JSONObjectWithData:responseObject options:kNilOptions error:nil];
NSString *valuKey=[NSString stringWithFormat :#"chaine%d",indexPath.row];
NSArray *testArray =[resultofData valueForKey:valuKey];
cd.categ=[[NSArray alloc]initWithArray:testArray];
cd.categArray=[[NSArray alloc]initWithArray:self.categoryArray];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
[[[UIAlertView alloc]initWithTitle:#":( " message:#"Pas d'internet !" delegate:nil cancelButtonTitle:#"Ok" otherButtonTitles:nil]show];
// NSLog(#"[HTTPClient Error]: %#", error.localizedDescription);
}];
[self.navigationController pushViewController:cd animated:YES];
[tableView cellForRowAtIndexPath:indexPath].selected = NO;
}
and in ProgViewController :
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
cprogCell *cell = [tableView dequeueReusableCellWithIdentifier:#"identifproecell"];
cell.heure.text = [[_categ objectAtIndex:indexPath.row]objectForKey:#"horaire_programme"];
cell.type.text = #"";
cell.desc.text = [[_categ objectAtIndex:indexPath.row]objectForKey:#"nom_programme"];
return cell;
}

Answer 1

You need to reload the UITableView once your asynchronous request has completed. Currently you push the UIViewController onto the stack and then datasource for it gets set later on, so the cell's only get loaded once you scroll.
To fix this, after you set the cd.categ and cd.categArray, make sure you either call [cd.tableView reloadData], or in the setters for categ or categArray call [self.tableView reloadData]

Answer 2

Too late, but I think you are handling the data to be displayed in the wrong place. For a period of time the user experience is to see a blank screen with no data.
It would be better to move all the data into the controller being pushed. So in your select, create the controller and set the data to be fetched as a property. In the ProgViewController, when inside viewDidAppear start the fetch and activate an activity indicator showing that it is busy. On success or failure stop the activity indicator. On success, call self.tableView.reloadData. On failure, raise the alert and pop the controller.
This way everything is being encapsulated and handled in the right place with the UI updating itself as its internal data state changes.
If you do the fetch from within the initial controller, then you should show its busy and only push the new controller once you have a result for it to display IMHO.