Question

this is probably simple but I’m stuck!

Basically I have a parent and child view controller, and I’m trying to pass data from the child to the parent.

//Child VC interface

@protocol ANSearchGetawayFilterDelegate
    -(void)selectedCell:(NSString *)cellTitle;
@end

@interface ANSearchGetawayFilterViewController : UIViewController <UITableViewDelegate,     UITableViewDataSource, UISearchBarDelegate>
{
   NSString* cellTitle;
}
@property (nonatomic, assign) id<ANSearchGetawayFilterDelegate> delegate;

@end

//Child VC implementation

@implementation ANSearchGetawayFilterViewController
@synthesize delegate = _delegate;

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *selectedCell = [tableView cellForRowAtIndexPath:indexPath];
    cellTitle = selectedCell.textLabel.text;
    [[self  delegate] selectedCell:cellTitle];

    [self dismissModalViewControllerAnimated:YES];
}

//Parent VC interface

#import "ANSearchGetawayFilterViewController.h"

@interface ANGetawayFilterViewController : UIViewController <ANSearchGetawayFilterDelegate>
{
    NSString* _cellText;
}

//Parent VC Implementation

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

//delegate method

    -(void)selectedCell:(NSString *)cellTitle
    {
        _cellText = cellTitle;
        NSLog(@"cell text %@", _cellText);
    } 

the delegate method is never called and when is NSLog the _cellText else where it comes up as null…what am I doing wrong? Thanks!

Answer 1

You are most likely creating a new instance of ANSearchGetawayFilterViewController when you present it and not configuring the delegate on it.

When you called

ANSearchGetawayFilterViewController *search = [[ANSearchGetawayFilterViewController alloc] init];
search.delegate = self;

you created an instance of ANSearchGetawayFilterViewController and then set the delegate up correctly, but you never stored this instance of ANSearchGetawayFilterViewController anywhere. So later on when you come to present it you call again

ANSearchGetawayFilterViewController *search = [[ANSearchGetawayFilterViewController alloc] init];

which gives you a completely different instance, which you then need to configure again. For example

ANSearchGetawayFilterViewController *search = [[ANSearchGetawayFilterViewController alloc] init];
ANSearchGetawayFilterViewController *search1 = [[ANSearchGetawayFilterViewController alloc] init];

NSLog(@"%d", search1 == search);

#=> 0

To fix update your code to be

- (BOOL)textFieldShouldBeginEditing:(UITextField*)textField;
{
    BOOL shouldBeginEditing = YES; 
    NSLog(@"text field should begin editing"); 

    ANSearchGetawayFilterViewController *myANSearchGetawayFilterViewController = [[[ANSearchGetawayFilterViewController alloc] init] autorelease]; 
    myANSearchGetawayFilterViewController.delegate = self;    // <--- configure the delegate

    [self presentModalViewController:myANSearchGetawayFilterViewController animated:YES];
    [self closeAllPickers]; 
    return shouldBeginEditing; 
}

I wouldn’t make it an ivar as the likelihood is you will present this viewController momentarily just to select some data and then get rid of it, so it is probably safe to discard it and make a new one each time.