iOS 6 pass data from TableView to Detail View - iphone

Question

I've a table view with some rows and each row has its Detail Disclosure button.
I want that when the user taps on that button, another table view (customized by storyboard) appears and shows some relative data.
From TableViewController.m
-(void)tableView:(UITableView *)tableView accessoryButtonTappedForRowWithIndexPath:(NSIndexPath *)indexPath {
DetailViewController *detailViewController = [[detailViewController alloc] init];
//creating a parse object
PFObject *checkin = [_dataSourceArray objectAtIndex:indexPath.row];
//getting data i want
NSString *trainNumb = [checkin objectForKey:#"trainNumber"];
//passing the data
detailViewController.trainNumber = trainNumb;
}
From the DetailTableViewController.m
- (void)viewDidLoad {
[_trainNumberLabel setText:_trainNumber];
}
The problem is that in the DetailTableView the NSString results to be null.
What I'm missing here? Thank you!

Answer 1

If this code actually compiles, this may be your problem:
DetailViewController *detailViewController = [[detailViewController alloc] init];
It should be:
DetailViewController *detailViewController = [[DetailViewController alloc] init];
But you shouldn't be alloc/initing your view controller in the first place. When you customize a view controller in Interface Builder, you've got to instantiate it like this if you want those customizations:
[self.storyboard instantiateViewControllerWithIdentifier:#"MyStoryboardIdentifier"]`
And you've got to set the controller's storyboard ID to "MyStoryboardIdentifier" or whatever identifier you want to use.
Also, as you've indicated in the comments, you've got a timing issue: your detail controller's viewDidLoad runs before you set the train number. A better approach would be to ensure that it works regardless of the sequence:
- (void)updateTrainNumberLabel
{
self.trainNumberLabel.text = self.trainNumber;
}
- (void)setTrainNumber:(NSString *)trainNumber
{
_trainNumber = trainNumber;
[self updateTrainNumberLabel];
}
- (void)viewDidLoad
{
...
[self updateTrainNumberLabel];
}
In other words, you configure your label in a separate method, in this case updateTrainNumberLabel, and when anything that could affect the label happens, e.g. the view loading or the number being changed, you call the method.