Question

I have a UINavigationController in which I am loading different view controllers. I want to know how can i access the elements (like labels etc) of my previous view.
Here is an eg.

View A
myLabel.text = @”first view”;

(User moves to view B)

View B
(user entered a message, that i need to display in View A)
something like ViewA.myLabel.text = @”user entered message”

I tried many things but was not able to find anything very useful. Please help..

I am using Xcode 4 without ARC and without storyboard.

Thanks
Sam

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Edited:

I want to update the property declared in viewController of View A and not the labels directly. My labels get updated using that property. Like while pushing the viewController we can pass the values as below.

ViewA *myView = [[ViewA alloc] init];
myView.title = @"View B" ;
myView.tableView.tag = 3;
myView.myTextView.text = @"Some Text";
[self.navigationController pushViewController:myView animated:YES];
[myView release];

Is there any way to pass these values to properties of ViewController of ViewA while popping ViewB and returning back to ViewA ?

The actual scenario is as follows: the user gets and option to write a message in textView or he can use the predefined templates. If he clicks on the templates button he is taken to a list of predefined templates where he can select any of the predefined message. Now I want that when the user click on any of the predefined message the view containing the list of predefined message gets popped of and the message he selected gets automatically populated in the textView of main view. what is the best approach to achieve this ?

TIA
Sam

Answer 1

You should set your AViewController as the delegate of your BViewController so you can message it back after a particular event. Using a delegate will also allow better decoupling of your ViewControllers.

In your BViewController, define a protocol like this :

BViewController.h :

@protocol BViewControllerDelegate <NSObject>
- (void)viewB:(UIViewController *)didEnterMessage:(NSString *)message;
@end

and add a delegate property :

@property (nonatomic, weak) id <BViewControllerDelegate> delegate;

When the user enter the message in your BViewController and hit the button that pops the BViewController to show to AViewController do this :

- (IBAction)messageEntered {
  if ([self.delegate respondsToSelector:@selector(viewB:didEnterMessage:)]) {
    [self.delegate viewB:self didEnterMessage:self.yourTextField.text];
  }
}

Your AViewController should implement the BViewControllerDelegate protocol like this :

AViewController.h :

@interface AViewController <BViewControllerDelegate>

When your AViewController creates the BViewController, it should set itself as its delegate before presenting it. Might look like this :

BViewController *bvc = [[BViewController alloc] init…];
bvc.delegate = self;

And finally, your AViewController should implement the viewB:didEnterMessage: method :

- (void)viewB:(UIViewController *)didEnterMessage:(NSString *)message {
  self.myLabel.text = message;
}

That’s the cleanest way to do that, IMHO.