How to access other viewcontrollers variables/properties in xcode

Question

I know similiar questions have been asked before, but please bear with me as I am totally new at Objective C (have good knowledge on C).

My case is that I have a tab bar controller with two windows. When I press a button in "second" I change a variable changeName. I want to use the value of changeName in my "first" view controller but stumbled on to some problems:

To reach the other viewcontroller I found this from SO (unfortunately I forgot where):

-(NSString *)newName{

// Create a UIStoryboard object of "MainStoryBoard_iPhone" named storyboard
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:(NSString *)@"MainStoryBoard_iPhone" bundle:(NSBundle *)nil];

// Create a UIViewController object of the wanted element from MainStoryBoard_iPhone
UIViewController *secondview = [storyboard instantiateViewControllerWithIdentifier:(NSString *)@"secondBoard"];

return secondview.changeName;
}

Which I have in my first.m. MainStoryBoard_iPhone is the name of the .xib/storyboard-file.

but no. Error says

Property 'changeName' not found on object of type 'UIViewController *'

In my second.h I have

 @property (readwrite, retain) NSString *changeName;

and in second.m

 @synthesize changeName;

All help is appreciated, but please keep in mind that I have only used OOP for two days. Thank you all in advance

EDIT: And what input should I have here?

 - (void)viewDidLoad
{
[super viewDidLoad];
mylabel.text = Name; // or [mylabel.text Name] or something? 
}

giorashc · Accepted Answer · 2012-06-08 08:27:13Z

5

You need to cast the view controller returned to your customized second view controller (as UIViewController does not have the property changeName).

So do the following :

// Create a UIViewController object of the wanted element from MainStoryBoard_iPhone
SecondViewController *secondview = (SecondViewController *)[storyboard instantiateViewControllerWithIdentifier:(NSString *)@"secondBoard"];

I assume SecondViewController is the name of your second controller.

answered Jun 8, 2012 at 8:27

giorashc

13.7k3 gold badges38 silver badges76 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

chwi Over a year ago

Thats what I wanted, but I see that I do not have to cast it if I use SecondViewController *secondview instead of UIViewController * secondview. But could you then explain to me what I have to insert in -(void)viewDidLoad to change my label? Functions/methods in OOP really confuses me.

giorashc Over a year ago

[myLabel setText:@"My Text"] should do the trick. Make sure myLabel is not nil (as this will still work with no errors but nothing will be actually set)

chwi Over a year ago

Thank you, but that will not set myLabel to the returned text from method Name, would it? And how do I assure that myLabel is not nil?

chwi Over a year ago

I tried [mylabel setText:[self Name]];, no errors but still no action on my label :\ Doing it your way did produce text, so it should work, shouldn`t it?

chwi Over a year ago

I see that my problem is that I have the tabbarcontroller in the middle which also has to get a pointer *tabBar, but UITabBarController class dont have instantiateViewControllerWithIdentifier so I don`t know how to succeed at this

|

Badr Bujbara · Accepted Answer · 2014-07-03 16:54:15Z

In my case I wanted to pass a string from FirstViewController to set a text field in SecondViewController, so:

1- In SecondViewController.h

@property (strong, nonatomic) IBOutlet UITextField *someTextField;// this is linked to a UITextField

2- In FirstViewController.m:

#import "SecondViewController.h"

3- I will do this after a press of a button in the FirstViewController:

SecondViewController *SecondView = [[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil];

//set fields values
    SecondView.someTextField.text = @"HeLLO from First";


UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController: SecondView];                  
//show AdView
   [self.navigationController presentViewController:nav animated:YES completion:nil];

4- This is it!

5- There is a case, if I'm in FirstViewController and wanted to set a string property in the SecondViewController with the same way, the string won't get the value till you press a some kinda button in SecondViewController, it won't get it like in viewDidLoad for example! don't know why.

Collectives™ on Stack Overflow

How to access other viewcontrollers variables/properties in xcode

2 Answers 2

6 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

6 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related