Transmit data through segue on tableView

Question

I'm working on an app where I want to display a tableView populated with users, and when the row is selected a new view is displayed containing a conversation (so basically a messaging app). For now I just want that when I touch a row on my FirstViewController, the SecondViewController is displayed with the name of the user selected on a label. But I can't get it to work because each time I touch a row, the indexPath is 0, si it is always the first user name that is displayed. Here is a part of my code:

#import "GSBChatViewController.h"
#import "GSBConversationViewController.h"



@interface GSBChatViewController ()
@property (weak, nonatomic) IBOutlet UITableView *userTableView;

@end

@implementation GSBChatViewController
@synthesize chatUsers;

- (void)viewDidLoad {
[super viewDidLoad];

GSBChatUsers *user1 = [[GSBChatUsers alloc]initWithName:@" John DOE" andPicture:@"photo.jpg" andLastMessage:@"Ca marche!"];
GSBChatUsers *user2 = [[GSBChatUsers alloc]initWithName:@"Justine DUBOIS" andPicture:@"photo.jpg" andLastMessage:@"Salut, ça va?"];
GSBChatUsers *user3 = [[GSBChatUsers alloc]initWithName:@"Jacques LAPORTE" andPicture:@"photo.jpg" andLastMessage:@"Réunion le 23 à 15h, c'est bon pour toi?"];
GSBChatUsers *user4 = [[GSBChatUsers alloc]initWithName:@"Guillaume DUPOND" andPicture:@"photo.jpg" andLastMessage:@"OK, parfait"];
GSBChatUsers *user5 = [[GSBChatUsers alloc]initWithName:@"Françoise MARTIN" andPicture:@"photo.jpg" andLastMessage:@"Tu as posé tes congés?"];
GSBChatUsers *user6 = [[GSBChatUsers alloc]initWithName:@"Jean-Jacques CELESTIN" andPicture:@"photo.jpg" andLastMessage:@"Je prends note"];

chatUsers = [[NSArray alloc]initWithObjects:user1,user2,user3,user4,user5,user6, nil];

}

- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}



#pragma mark - Navigation


- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {

NSIndexPath *indexPath = [self.userTableView indexPathForCell:sender];
NSLog(@"Path: %@",indexPath);

GSBConversationViewController *destVC = [segue destinationViewController];
GSBChatUsers *selectedUser =[chatUsers objectAtIndex:indexPath.row];

NSLog(@"%ld",[self.userTableView indexPathForCell:sender].row);
NSString *userName = selectedUser.name;

NSLog(userName);
destVC.Test=userName;

}


#pragma mark - Datasource

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {

// Retourne le nombre d'éléments de notre liste
NSLog(@"Number of rows: %ld",chatUsers.count);
return [chatUsers count];

}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{

// Instancie notre cellule par son identifier
GSBTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"userCell"];

// On récupère l'item que l'on va traiter
GSBChatUsers *user = [chatUsers objectAtIndex:indexPath.row];

// On affecte les valeurs de notre user aux éléments de notre cellule
[cell.userName setText:user.name];
[cell.profilePicture setImage:[UIImage imageNamed:user.picture]];
[cell.lastMessage setText:user.lastMessage];
NSLog(@"%@",chatUsers);

return cell;

}




- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
NSLog(@"%@",_cellTitle);
//[self performSegueWithIdentifier:@"conversationSegue" sender:[chatUsers objectAtIndex:indexPath.row]];

}


@end

I looked at this answer as well as this one but none of them helped. (Well they helped because beforehand I couldn't even get the label's text to change).

Disclaimer: This is for a school project, and I'm one hundred percent allowed to ask for help on the Internet. As english is not my native language maybe I'm not clear on some points, please let me know if you need further informations.

Thanks for your help!

Answer 1

it looks like the tableView in the storyboard is not connected to the outlet userTableView. therefore the row NSIndexPath *indexPath = [self.userTableView indexPathForCell:sender]; does not return the correct result.

go to your storyboard, connect the outlet to the tableview and try again!

Answer 2

If you dragged a segue on the storyboard from your table cell prototype to the view controller you want to push to, then you are halfway there. However, the segue will be triggered before the UITableViewDelegate is informed that the user "didSelectRowAtIndexPath", so navigation to the next view controller will happen before your code in that delegate method runs.

The solution is to override prepareForSegue:sender: in your FirstViewController. In this case, the sender will be the table cell that was tapped.

Your implementation could look something like this:

- (void)prepareForSegue:(UIStoryboardSegue *)segue
             sender:(id)sender {
    GSBTableViewCell *cell = (GSBTableViewCell *)sender;
    SecondViewController *destination = ((SecondViewController *)segue.destinationViewController);
    destination.view;  // Sadly, this is required to force the outlets to be connected in the destination view controller before you try to access them
    destination.userNameLabel.text = cell.userName.text;
}