Destination value is null when sending value using "performSegueWithIdentifier" - ios

Question

I have three navigation buttons in a view controller, two of which I process locally and one which launches an edit view controller. I have created a segue from the body of the first UITableView to the Navigation Controller of the destination view controller (the edit view controller).
The button works fine (i.e. launches the edit view) but it doesn't receive the string I send to it. Could someone please help. I have tried all of the suggestions given to other related questions but cannot seem to fix this. Following is the related code.
Source controller.h:
#import <UIKit/UIKit.h>
#import "EQHorseAddViewController.h"
#import "EQDatabase.h"
#interface EQHorseDetailViewController : UITableViewController
#property (strong, nonatomic) EQHorseAddViewController *addViewController;
Source controller.m:
#import "EQHorseDetailViewController.h"
#interface EQHorseDetailViewController ()
#end
#implementation EQHorseDetailViewController
#synthesize addViewController;
-(void)viewDidLoad
{
[super viewDidLoad];
UIBarButtonItem *deleteItem= [[UIBarButtonItem alloc]
initWithBarButtonSystemItem:UIBarButtonSystemItemTrash
target:self
action:#selector(deleteHorse:)];
UIBarButtonItem *editItem = [[UIBarButtonItem alloc]
initWithBarButtonSystemItem:UIBarButtonSystemItemEdit target:self
action:#selector(editHorse:)];
NSArray *actionButtonItems = [[NSArray alloc] initWithObjects:deleteItem, editItem,
nil];
self.navigationItem.rightBarButtonItems = actionButtonItems;
}
-(void)editHorse:(id)sender
{
NSLog(#"EditingHorse");
self.addViewController= [[EQHorseAddViewController alloc] init];
addViewController.resultSegue = #"Edit Horse Details";
[self performSegueWithIdentifier:#"EditHorseDetails" sender: self];
}
Destination View Controller.h:
#import <UIKit/UIKit.h>
#import "EQHorseDetailsInfo.h"
#import "EQDatabase.h"
#class EQHorseAddViewController;
#protocol EQHorseAddViewControllerDelegate <NSObject>
- (void) eqHorseAddViewControllerDidCancel:(EQHorseAddViewController *)controller;
- (void)eqHorseAddViewControllerDidSave: (EQHorseAddViewController *)controller;
#end
#interface EQHorseAddViewController : UITableViewController
<EQHorseAddViewControllerDelegate>
#property (strong, nonatomic) EQHorseAddViewController *addViewController;
#property (nonatomic, weak) id <EQHorseAddViewControllerDelegate> delegate;
#property (strong,nonatomic) NSString *resultSegue;
Destination View Controller.m
#import "EQHorseAddViewController.h"
#import "EQDatabase.h"
#import "EQHorseDetailsInfo.h"
#interface EQHorseAddViewController ()
#end
#implementation EQHorseAddViewController
#synthesize resultSegue;
- (void)viewDidLoad
{
NSLog(#"resultSegue %#",resultSegue);
}
Thanking you in advance.

Answer 1

It looks like you're referring to the code in editHorse:, which allocates an EQHorseAddViewController and sets a property on it. The problem with that code is that the view controller it allocates bears no relation to the vc destination of the segue. That method simply creates a vc and then instantly discards it.
Remove the allocation and instead implement prepareForSegue:. The segue object passed to that method will have a property called destinationViewController. That's the view controller that's about to be pushed onto the navigation. That's the one on which you should set the resultSegue property.
-(void)editHorse:(id)sender
{
NSLog(#"EditingHorse");
[self performSegueWithIdentifier:#"EditHorseDetails" sender: self];
}
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([segue.identifier isEqualToString:#"EditHorseDetails"]) {
EQHorseAddViewController *vc = segue.destinationViewController;
vc.resultSegue = #"Edit Horse Details";
}
}

Answer 2

You need to define the new controller as follows:
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:#"Main" bundle:nil];
EQHorseAddViewController *ivc = [storyboard instantiateViewControllerWithIdentifier:#"EditHorseDetails"];
ivc.resultSegue = #"Edit Horse Details";
Perhaps you'll need this method too
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([[segue identifier] isEqualToString:#"EditHorseDetails"]) {
// Get destination view
EQHorseAddViewController *vc = [segue destinationViewController];
vc.resultSegue = #"Edit Horse Details";
}
}

Answer 3

-(void)editHorse:(id)sender
{
NSLog(#"EditingHorse");
resultSegue = #"Edit Horse Details";
[self performSegueWithIdentifier:#"EditHorseDetails" sender: self];
}
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
UINavigationController *navigationController = segue.destinationViewController;
EQHorseAddViewController *addViewController = [navigationController viewControllers]
[0];
// Get destination view
NSLog(#"ResultSegue in Prepare - %#",resultSegue);
addViewController.resultSegue = #"Edit Horse Details";
}