Question

I am trying to access properties of an object (person’s firstName) which is stored in an array and assign it to labels in a seperate view Controller (SplitMethodViewController). The name value is successfully assigned here. Code snippet as below:

In the initial view controller (before displaying the modal view controller containing the UILabel):

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    int row = [indexPath row];
    Person *thisPerson = (Person *)[self.personArray objectAtIndex:row];

    SplitMethodViewController *smvc = [[SplitMethodViewController alloc]initWithNibName:nil bundle:nil];
    smvc.nameLabel.text = [[NSString alloc] initWithFormat:@"%@", thisPerson.firstName];

    //This lines returns the value I want, showing that assignment is working till this point
    NSLog(@"The name label is %@", smvc.nameLabel.text);

    [self presentModalViewController:smvc animated:YES];

    [smvc release];

}

However, the values became blank when I check in the splitMethodViewController (checked in ViewDidLoad Method)

@interface SplitMethodViewController : UIViewController 
{
    UILabel *nameLabel;
}

@property (nonatomic, retain) IBOutlet UILabel *nameLabel;
@end

@implementation SplitMethodViewController

@synthesize nameLabel;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
    // Custom initialization.
    self.nameLabel = [[UILabel alloc] init];
    }
    return self;
}

- (id)init 
{
    return [self initWithNibName:nil bundle:nil];
}
- (void)viewDidLoad 
{
    //name label returning nothing here.
    NSLog(@"namelabel is %@",self.nameLabel.text);

    [super viewDidLoad];
}
@end

I am sure I made some silly mistake somewhere. I have tried deleting all the outlets and labels and re-created just one name label and outlet. But I am still hitting this same issue.

Any help will be appreciated!

Answer 1

Did you actually allocate and instantiate the nameLabel and evenBillAmountLabel once you instantiate the SplitMethodViewController? In Objective-C messages (method calls) can be sent to nil (non-existant objects) without returning any errors, but also without any results.

Make sure the -init method on SplitMethodViewController looks somewhat like this:

// this is the designated initializer of most view controllers, 
// do initialization here ...
- (id)initWithNibName:(NSString *)nibName bundle:(NSBundle *)nibBundle 
{
    self = [super initWithNibName:nibName bundle:nibBundle]; 
    if (self)
    {
        nameLabel = [[UILabel alloc] init];
        evenBillAmountLabel = [[UILabel alloc] init];
        // add other stuff you need to initialize ...
    }
    return self;
}

- (id)init 
{
    // since we don't wanna re-implement allocation and instantiation for every 
    // initializer, we call the 'designated initializer' with some default values,
    // in this case the default nibName and bundle are nil.
    return [self initWithNibName:nil bundle:nil];
}

- (void)dealloc 
{
    [nameLabel release];
    [evenBillAmountLabel release];
    [super dealloc];
}

Be sure to read about designated initializers if this is new to you and if this was related to your issue. Here’s a link to Apple’s documentation on the subject.