Updating UILabel from another View Controller

Question

Hi i am kind of stuck at the moment as to sending UILabel data across from one view controller to another coming from a collection view cell. Here is my current code of which i get no errors? May seem obvious to someone who knows what they are doing but do i need to somehow declare on the second view controller that i am setting the UILabel from another VC?

Here is my current code as follows:

GroupsViewController.m

#import "GroupsViewController.h"
#import "GroupsHomeViewController.h"
#import "CustomCell.h"

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
    [self performSegueWithIdentifier:@"GroupsHomeSegue" sender:indexPath];
}

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

    if ([segue.identifier isEqualToString:@"GroupsHomeSegue"])
    {
        NSIndexPath* indexPath = [[self.GroupsCollectionView indexPathsForSelectedItems]firstObject];
        if(indexPath !=nil)
        {
            NSString *selectedImage = arrayOfImages [indexPath.item]; //collect image
            GroupsHomeViewController *groupsHomeVC = segue.destinationViewController; //set D.V.C
            groupsHomeVC.logoImage = [UIImage imageNamed: selectedImage]; //set image
            groupsHomeVC.groupLabel.text = arrayOfDescriptions[indexPath.item ]; //set text

        }
    }
}

GroupsHomeViewController.h

@interface GroupsHomeViewController : UIViewController<UITableViewDataSource, UITableViewDelegate>

@property (strong, nonatomic) IBOutlet UIImageView *logoImageView;
@property (strong, nonatomic) UIImage *logoImage;
@property (strong, nonatomic) IBOutlet UILabel *groupLabel;
@end

GroupsHomeViewController.m

#import "GroupsHomeViewController.h"

@interface GroupsHomeViewController ()

@end

@implementation GroupsHomeViewController

-(void)viewDidLoad{ 
    [super viewDidLoad];
}

- (void)viewWillAppear:(BOOL)animated {
    self.logoImageView.image = self.logoImage;
}

Many Thanks in advance for your time and patience.

Yeah it sets the image perfectly no problems, I just can't get it to set the label on the secondary view controller — Lee Sugden, Jun 02 '16 at 18:07

score 1 · Answer 1 · answered Jun 02 '16 at 18:09

First thing in GroupsHomeViewController.h create one property as

@property (nonatomic, strong)NSString *descriptionName;

then update your method to

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

    if ([segue.identifier isEqualToString:@"GroupsHomeSegue"])
    {
        NSIndexPath* indexPath = [[self.GroupsCollectionView indexPathsForSelectedItems]firstObject];
        if(indexPath !=nil)
        {
            NSString *selectedImage = arrayOfImages [indexPath.item]; //collect image
            GroupsHomeViewController *groupsHomeVC = segue.destinationViewController; //set D.V.C
            groupsHomeVC.logoImage = [UIImage imageNamed: selectedImage]; //set image
            groupsHomeVC.descriptionName = arrayOfDescriptions[indexPath.item ]; //set text

        }
    }
}

Now in GroupsHomeViewController.m update this

#import "GroupsHomeViewController.h"

@interface GroupsHomeViewController ()

@end

@implementation GroupsHomeViewController
@synthesize descriptionName;
-(void)viewDidLoad{ 
    [super viewDidLoad];
}

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    self. groupLabel.text = descriptionName;
}

This will surely help. In your case text is assigning to label but when you move to lifecycle methods of GroupsHomeViewController gets called. So here your UILabel is getting initialised and your are setting text before it so its not displaying it.

Creating NSString property will surely help you out.

score 1 · Accepted Answer · answered Jun 02 '16 at 18:24

1

Because At this time, the GroupsHomeViewController is not loaded in the memory yet, that's why you are facing this issue. Instead of directly passing value to UILabel, try passing text using NSString. Declare

@property (strong,nonatomic) NSString *valueToPass;

in GroupsHomeViewController . Then pass value to string using below code

NSString *selectedImage = arrayOfImages [indexPath.item]; //collect image
GroupsHomeViewController *groupsHomeVC = segue.destinationViewController; //set D.V.C
groupsHomeVC.logoImage = [UIImage imageNamed: selectedImage]; //set image
// pass string to next viewController's NSString object.            
groupsHomeVC.valueToPass = arrayOfDescriptions[indexPath.item ];

Then in viewDidLoad of GroupsHomeViewController ,set string on UILabel like this self.groupLabel.text=self.valueToPass. Try doing this.

answered Jun 02 '16 at 18:24

Sushil Sharma

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Would it also be possible to use the same string and set it as the view controller title on the top bar? – Lee Sugden Jun 02 '16 at 18:37
Yes, you can simply pass this string as navigation bar title. – Sushil Sharma Jun 02 '16 at 18:39
Please could you be so kind and provide me with me an example? – Lee Sugden Jun 02 '16 at 18:40
You can refer this link. Will surely help you http://stackoverflow.com/questions/6154237/how-to-set-the-title-of-a-navigation-bar-programatically – Sushil Sharma Jun 02 '16 at 18:43
Thank you very much for all off your help! – Lee Sugden Jun 02 '16 at 18:47

Updating UILabel from another View Controller

2 Answers2