can't get a view controller property to another view controller - ios

Question

i have 2 view controllers:
StackTableViewController.m:
#interface StackTableViewController () <NSFetchedResultsControllerDelegate>
#property (nonatomic, strong) NSFetchedResultsController *fetchedResultController;
#end
#implementation StackTableViewController
- (void)viewDidLoad {
[super viewDidLoad];
[self.fetchedResultController performFetch:nil];
NSIndexPath *indexPath = [NSIndexPath indexPathForItem:0 inSection:0];
Target *record = [self.fetchedResultController objectAtIndexPath:indexPath];
self.currentTarget = record.body;
}
HomeViewController.m
#import "HomeViewController.h"
#import "CreateViewController.h"
#import "StackTableViewController.h"
#interface HomeViewController ()
#property (strong, nonatomic) IBOutlet UILabel *targetLabel;
#end
#implementation HomeViewController
- (void)viewDidLoad {
[super viewDidLoad];
StackTableViewController *vc = [[StackTableViewController alloc] init];
NSString *current = vc.currentTarget;
// Do any additional setup after loading the view.
self.targetLabel.text = current;
}
but something wrong with the HomeViewController because it's not populating the label..
how can i solve it?
tnx

Answer 1

You should probably update the label's text within ViewWillAppear of the StackTableViewController
Also, is currentTarget set up in StackTableViewController's init method? If not, it won't be initialized and that would be why you're not getting anything in HomeViewController's label

Answer 2

Explanation
viewDidLoad is not called instead, or before the init! It's called sometime after the init method finishes.
What happens:
- (void)viewDidLoad {
[super viewDidLoad];
StackTableViewController *vc = [[StackTableViewController alloc] init]; // init is called on vc object
NSString *current = vc.currentTarget; // ViewDidLoad was not yet called on vc object!
self.targetLabel.text = current;
}
/// ViewDidLoad will be called on vc object sometime after leaving this method!
What happens is:
You call StackTableViewController *vc = [[StackTableViewController alloc] init]; which sends a message init to the object.
You don't have init method in your implementation so the init of superclass (UIViewController) is called. When you instantiate your ViewController it begins loading view. Only after it's done loading ViewDidLoad will be called.
Please read any article on ViewController's lifecycle .
Solution
Fastest solution to your problem: create a delegate in your table, and inform when it's done loading using delegates, like this:
Table view controller
#implementation StackTableViewController
{
id<TargetChangedDelegate> _myDelegate;
}
-(id)initWithDelegate:(id<TargetChangedDelegate>)delegate
{
_myDelegate= delegate;
}
- (void)viewDidLoad {
[super viewDidLoad];
[self.fetchedResultController performFetch:nil];
NSIndexPath *indexPath = [NSIndexPath indexPathForItem:0 inSection:0];
Target *record = [self.fetchedResultController objectAtIndexPath:indexPath];
self.currentTarget = record.body;
// inform your delegate
[_myDelegate targetChanged];
}
Home view controller
#interface HomeViewController () <TargetChangedDelegate>
#property (strong, nonatomic) IBOutlet UILabel *targetLabel;
#end
#implementation HomeViewController
- (void)viewDidLoad {
[super viewDidLoad];
StackTableViewController *vc = [[StackTableViewController alloc] initWithDelegate:self];
}
- (void)targetChanged
{
NSString *current = vc.currentTarget;
// Do any additional setup after loading the view.
self.targetLabel.text = current;
}