iphone development: how to set a property of an another viewController then reach it

Question

Lets say I have two viewcontrollers ViewControllerA and ViewControllerB when I press a button from viewcontrollerA it is pushing to viewControllerB. However before pushing I want to set a property of viewControllerB from viewControllerA. But all I get is nil value when I check the variable from viewControllerB. What I do is;

In ViewControllerA:

VCB = [[ViewControllerB alloc]init];
[VCB setPropertyOfViewControllerB:someString];
NSLog(@"value: %@", VCB.PropertyOfViewControllerB); // Here I observe the correct value so I set successfully

but the thing is I also want to reach it from viewControllerB but I get nil for the variable.

In ViewControllerB:

//I already defined in h file as property
NSString *PropertyOfViewControllerB;
@property(nonatomic, retain) NSString *PropertyOfViewControllerB;

But when I try to check the value in viewDidLoad method of ViewControllerB

NSLog(@"value: %@", PropertyOfViewControllerB);//here I get null not the value I set at viewControllerA

Probably I miss a small point I could not figure out. Any help would be awesome. Thanks.

Edit: I am using storyboards. I push with the following code:

    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle: nil];
    lvc = [storyboard instantiateViewControllerWithIdentifier:@"mainManu"];
    [self.navigationController pushViewController:lvc animated:YES];

Did you use a Storyboard? Please also show the code, how you push your ViewController. — xapslock, Apr 17 '13 at 15:03
@xapslock yes I use storyboard. I edited the answer to show how I push — death7eater, Apr 17 '13 at 15:07
maybe this is useful: Passing Data between View Controllers http://stackoverflow.com/questions/5210535/passing-data-between-view-controllers — TomCobo, Apr 17 '13 at 15:09
@TomCobo thanks I looked at it before. it is really useful but i want to figure out why my approach does not work — death7eater, Apr 17 '13 at 15:14

score 7 · Accepted Answer · answered Apr 17 '13 at 15:13

7

If you use VCB = [[ViewControllerB alloc]init]; but push via Storyboard, then VCB is not the same ViewController used in Storyboard. Try this:

 - (void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
     if ([[segue identifier] isEqualToString:@"yourSegueName"]) {
         ViewControllerB *vc = [segue destinationViewController];
         [vc setPropertyOfViewControllerB:@"foo"];
     }  
}

answered Apr 17 '13 at 15:13

xapslock

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yes I see your point but the thing is I dont want to use that delegate method because in my application when a button pressed first I want make some assignments (data coming from a webservice) so I have to be sure that all the data is collected and assigned to the properties then i want to push. but in your answer it pushes immediately. – death7eater Apr 17 '13 at 15:20
No, prepareForSegue: will automatically called before every VC will be pushed. You can do your stuff, webservice, etc. and then call [self performSegueWithIdentifier:@"yourSegueName" sender:self]; – xapslock Apr 17 '13 at 15:24
I think I solved the problem with your approach I just added [vc setPropertyOfViewControllerB:@"foo"]; in my version of pushing and it worked...thanks – death7eater Apr 17 '13 at 15:25

iphone development: how to set a property of an another viewController then reach it

1 Answers1