Question

Hey there I have been working on a transit app for some time and have been stuck with this issue for a while now.

I am using iOS 5 and a storyboard. Basically I have a UITableView that displays favorite bus stop locations, when a user selects a row I use:

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    Favorite *favorite = [self.favoriteItems objectAtIndex:indexPath.row];

    stopString = favorite.title;
    routeString = favorite.subtitle;
}

With the stop and route information of the cell the user chose I then prepare for a segue that corresponds to a segue on my storyboard, pushing a detail view controller that uses the stop name and route name to display times from a plist.

I am fairly new to Objective C and iOS so I am using a segue that my friend told me would work, however, it might be the problem. The segue looks like this:

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    UIViewController *destination = segue.destinationViewController;
    if ([destination respondsToSelector:@selector(setDelegate:)])
    {
        [destination setValue:self forKey:@"delegate"];
    }
    if ([destination respondsToSelector:@selector(setSelection:)])
    {
        NSString *route = routeString;
        NSDictionary *selection1 = [NSDictionary dictionaryWithObjectsAndKeys:route, @"route", stopString, @"stop", nil];
        [destination setValue:selection1 forKey:@"selection"];
    }
}

After the segue in my DetailViewController I grab the stop and route information in the view DidLoad:

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.

    route = [selection objectForKey:@"route"];
    stopName = [selection objectForKey:@"stop"];

    NSLog(@"stopName: %@", stopName);
    NSLog(@"routeName: %@", route);
}

Here is where my problems arise. When I run the simulator and click on an a cell in my table view, I am pushed to the DVC, however, the stopName and routeName are both null, so no information was sent or received. BUT, if I go back to the table and click another cell, the routeName and stopName are filled with the information that should have sent the first time I clicked a cell. If I continue this process it continues to send the information for the cell tapped previously, not currently.

So basically information is sending but only after I go through the segue twice. Obviously I want it to send the information and receive it the first time, but it is delayed and driving me nuts. I appreciate any help someone can give me as I have been searching the internet for days now trying to fix this issue, thank you so much in advance for any assistance!

Answer 1

prepareForSegue: is being called before didSelectRowAtIndexPath:. This is why the values you see always are lagging behind.

The better solution is to get the stopString and routeString values in your prepareForSegue: method (and not use didSelectRowForIndexPath: at all). The key to doing this is to realize that the sender parameter value being passed to prepareForSegue: is the UITableViewCell that was tapped. You can use the UITableView method indexPathForCell to get the cell’s indexPath in your table, and then use that to look up the data in your favoriteItems array.

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{    
    UITableViewCell *cell = (UITableViewCell*)sender;
    NSIndexPath *indexPath = [self.tableView indexPathForCell:cell];   
    Favorite *favorite = [self.favoriteItems objectAtIndex:indexPath.row];

    stopString = favorite.title;
    routeString = favorite.subtitle;

    UIViewController *destination = segue.destinationViewController;
    if ([destination respondsToSelector:@selector(setDelegate:)])
    {
        [destination setValue:self forKey:@"delegate"];
    }
    if ([destination respondsToSelector:@selector(setSelection:)])
    {
        NSString *route = routeString;
        NSDictionary *selection1 = [NSDictionary dictionaryWithObjectsAndKeys:route, @"route", stopString, @"stop", nil];
        [destination setValue:selection1 forKey:@"selection"];
    }
}