Passing variables in xcode returns null

Question

I checked the questions here on stack overflow and i do it in the same way but still returns NULL

In the first view

in the firstviewcontroller.h i have

@property (nonatomic, copy) NSString *Astring;

in the firstviewcontroller.m

#import "SecondViewController.h"
...
@synthesize Astring = _Astring;
...

- (IBAction)filterSearch:(id)sender {
NSlog(@"%@",Astring)

      }

in the secondviewcontroller.m

#import firstviewcontroller.h
...
...
FirstViewController *controller = [[FirstViewController alloc]initWithNibName:@"FirstViewController" bundle:nil];
 controller.Astring = @"YES";

So basicly i make a variable in the firstviewcontroller and pass in the secondviewcontroller the variable to second view,but it returns NULL always...

Is my logic wrong or is it something else

There's something wrong with your #import, it seems like you inverted them. It won't correct the problem, but the question will be more understandable. — rdurand
Besides that is it always needed to make a variable and pass the variable to it...cant you see it in the other view ? — MichaelAngelo
Your code is confusing. You declared a property called "AString", then synthesized it assigning "_Astring" as an instance variable. In SecondViewController you set value @"YES" to the property, but in your filterSearch method in NSLog() you use different variable "Astring" which is not a property, or corresponding instance variable. Do you also have a "Astring" variable somewhere or it's just a typo? — Yarlik

Josiah Josiah · Accepted Answer · 2012-12-04T16:14:33

Here's the problem. You are indeed changing the string value of AString, but on a new instance of a view controller. This line: FirstViewController *controller = [[FirstViewController alloc]initWithNibName:@"FirstViewController" bundle:nil]; is creating a new instance of the controller. Therefore, the existing controller's view controller has the same property.

What you need to do then, is find a way to get the instance of your firstViewController.

In secondViewController.h, add this property.

#import "firstViewController.h"
 ...
@property (nonatomic, strong) firstViewController *firstController;

Then, in secondViewController.m, you can just call the change in string with firstController, which will contain the instance you're after. I believe it should be something like this now:

firstController.Astring = @"YES"

Cheers!

Passing variables in xcode returns null

1 Answers