Set Label text equals to variable - ios

Question

I'm writing a program for fun, and in it I have a UIViewController with four buttons, they all send the user to another view, but depending on what button is pressed, I want the label in that other view to have a different text. To do that, I decided to have the label's text to be set equals to a NSString variable, and that variable is set to a certain text depending on what button is pressed. So I have this:
UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:#"Main" bundle:nil];
UIViewController *vc = [mainStoryboard instantiateViewControllerWithIdentifier:#"resultScreen"];
[self presentViewController:vc animated:YES completion:nil];
_myLabel.text = [NSString stringWithFormat:myText];
In which myText is the NSString variable I want the label to be set to.
Everything seems to be in order, but the label won't have it's text changed. If I try to change it's text inside the viewDidLoad function, though, it works just fine, so I don't know what is happening.
Any idea of what I might need? If you need more info, just comment what you want and I will try to provide it.

Answer 1

You cannot update UI of other controller from current one - you can set variables and later on in viewDidLoad or viewWillAppear you can assign those values to UI
In File: FirstViewController.m
UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:#"Main" bundle:nil];
SecondViewController *vc = [mainStoryboard instantiateViewControllerWithIdentifier:#"SecondViewController"];
vc.passedText = #"Hello Next";
[self.navigationController pushViewController:vc animated:YES];
In File: SecondViewController.h
#interface SecondViewController : UIViewController
#property (strong, nonatomic) IBOutlet UILabel *myLabel;
#property (strong, nonatomic) NSString *passedText;
In File: SecondViewController.m
-(void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:YES];
self.myLabel.text = self.passedText;
}

Answer 2

I think you need to set your ViewController's property before calling the:
[self presentViewController:vc animated:YES completion:nil];
If you set it after presenting the view, you have to manually refresh the view, which is a bit of an overkill. Just set it before presenting the view. So it would look like:
UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:#"Main" bundle:nil];
ResultScreenViewController *vc = (ResultScreenViewController *)[mainStoryboard instantiateViewControllerWithIdentifier:#"resultScreen"];
vc.customTitleLabel.text = [NSString stringWithFormat:myText];
[self presentViewController:vc animated:YES completion:nil];
In your ViewController header file:
#property (nonatomic, strong) UILabel *customTitleLabel;

Answer 3

First Create a subclass of a UIViewController with a custom label:
#interface NextViewController : UIViewController
#property (nonatomic, strong) UILabel* customLabel
#end
Now back to your code. You simple cast the UIViewController you get to the subclass you created so you can access the label inside you view controller.
UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:#"Main" bundle:nil];
NextViewController* nextVC = (NextViewController*)[mainStoryboard instantiateViewControllerWithIdentifier:#"resultScreen"];
nextVC.customLabel.text = [NSString stringWithFormat:myText];
[self presentViewController:nextVC animated:YES completion:nil];

Answer 4

Ok, with the help of one of the answers here I found I solution that works for me. Before, when I had
UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:#"Main" bundle:nil];
UIViewController *vc = [mainStoryboard instantiateViewControllerWithIdentifier:#"resultScreen"];
[self presentViewController:vc animated:YES completion:nil];
_myLabel.text = [NSString stringWithFormat:myText];
I didn't realise that the resultScreen wasn't linked to UIViewController, but to ViewContronller. So all I needed to do was change the vc declaration to
ViewController *vc = (ViewController *)[mainStoryboard instatiateViewControllerWithIdentifier:#"resultScreen:];
So then all I needed to do was change the label's text at the ViewDidLoad module. It works just fine for me now.

Answer 5

Its simple..
if ([_mylabel.text isEqualToString: myText)
{
//--- Now process your method here. Show alert or what else you need
}

Answer 6

try this. I think that accessing UIlabel directly of other UIViewController is not a good approach. Follow this & it will definitely work.
UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:#"Main" bundle:nil];
resultScreen *vc = [mainStoryboard instantiateViewControllerWithIdentifier:#"resultScreen"];
vc.strText = myText;
[self presentViewController:vc animated:YES completion:nil];
In your resultScreen view controller create a NSString property.
resultScreen.h
#property (retain, nonatomic) NSString *strText;
resultScreen.m
-(void)viewDidLoad
{
self.myLabel.text = self.strText;
}

Answer 7

you are trying to set the labelText before presenting the second View.
Before view gets loaded into the memory, its all outlets are nil.
so use the NSString variable in second view, and try to set the value of that variable,and then in
viewWillAppear: method assign the value of string variable to the labelText, this will definitely work.
Cheers!