Passing string back in popViewControllerAnimated

Question

I have a UIViewController(1), I press on a view in that controller and it then push's another UIViewController(2) with a full screen UITableView in it.

I then press on a cell in the UITableView and want to pass back to UIViewController(1) a string in the UITableView. I have tried using the below delegete method but it doesn't work, please can somebody advise.

UIViewController2.h
@protocol SecondDelegate <NSObject>
-(void) secondViewControllerDismissed:(NSString *)stringForFirst;
@end

@interface ViewController2 : UIViewController
{
    id myDelegate;
}
@property (nonatomic, assign) id<SecondDelegate> myDelegate;
@end

and

UIViewController2.m (inside didSelectRowAtIndexPath)
    [self.myDelegate secondViewControllerDismissed:@"the string I'm passing"];

and

UIViewController1.h
import "ViewController2.h"
    @interface ViewController1 : UIViewController <SecondDelegate>

@end

and

UIViewController1.m
- (void)secondViewControllerDismissed:(NSString *)stringForFirst
{
    NSString *myString = stringForFirst; 
    self.myLabel.text = myString;
}

What is your question? Where does something not work as intended? Did you actually set the `myDelegate` property? You should maybe change your `@propery` to `(weak)`... and remove the `id myDelegate` line inside the `@interface` — luk2302, May 03 '15 at 20:02
My question is in the last piece of code, why does self.myLabel.text != myString. It doesn't pass the string — James Walker, May 03 '15 at 20:03
when i tap on a view in ViewController1, it performs a segue to ViewController2 — James Walker, May 03 '15 at 20:06
- (void)secondViewControllerDismissed:(NSString *)stringForFirst is never called in ViewController1 — James Walker, May 03 '15 at 20:06
whilst debugging with breakpoint i find the above method is never called in ViewController1, do I just need to call it on viewDidAppear? — James Walker, May 03 '15 at 20:08

score 1 · Accepted Answer · edited May 23 '17 at 12:06

1

A few things:

remove id myDelegate; inside your @interface ViewController2
change your @property (nonatomic, assign) id... to @property (nonatomic, weak) id..., that is just safer (see why)

Regarding your question: you present the view via a segue!? Therefore you need to overwrite the prepareForSegue method, extract the destinationViewController from the segue and set its delegate property to self. Without that, your ViewController2 never gets a valid delegate set. All that needs to be done in the viewController presenting the ViewController2:

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    [super prepareForSegue:segue sender:sender];
    if ([segue.identifier isEqualToString:@"yourCustomSegueIdentifier"]) {
        ViewController2 *controller = (ViewController2*)segue.destinationViewController;
        controller. myDelegate = self;
    }
}

Either set an identifier of your segue in the storyboard and use the same identifier in the ode above or remove the if all together (unclean).

edited May 23 '17 at 12:06

Community

1
1

answered May 03 '15 at 20:10

luk2302

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yes I present via a segue, please could you provide example code for your suggestion? – James Walker May 03 '15 at 20:12
I am getting "Property 'delegate' not found on object of type 'UIViewController *' – James Walker May 03 '15 at 20:15
i added it in ViewController1.m – James Walker May 03 '15 at 20:17
and it is getting called when you touch a button or do *something* to show ViewController2 ? – luk2302 May 03 '15 at 20:17
yes, prepareForSegue is called automatically when you call performSegueWithIdentifier – James Walker May 03 '15 at 20:20
I changed it to set the `myDelegate`, was a minor typo... Does it work now? – luk2302 May 03 '15 at 20:21
HAZAR! Much internet love to you! Many Thanks – James Walker May 03 '15 at 20:22
Why remove `nonatomic` from the properly declaration? Does it need to be `atomic` (the default)? – rmaddy May 03 '15 at 20:38
@rmaddy well, you are right, atomic/nonatomic slipped by, I primarily wanted him to write weak and not to include assign... will update. – luk2302 May 03 '15 at 20:41

Passing string back in popViewControllerAnimated

1 Answers1