Question

In a view, let’s call it firstView I created a secondView as follows and pushed it if certain thing happened in the firstView:

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


    [self.navigationController pushViewController:secondVC animated:YES];
    [secondVC release];

Now when I’m in the secondView if let say a button is pressed I want to go back to firstView and also pass back a value from secondView to the firstView (let say an integer value of a textfield from secondView to the firstView).

Here is what I tried:

@protocol SecondViewControllerDelegate;

#import <UIKit/UIKit.h>
#import "firstViewController.h"

@interface SecondViewController : UIViewController <UITextFieldDelegate>
{
    UITextField *xInput;
    id <SecondViewControllerDelegate> delegate;
}

- (IBAction)useXPressed:(UIButton *)sender;

@property (assign) id <SecondViewControllerDelegate> delegate;

@property (retain) IBOutlet UITextField *xInput;

@end

@protocol SecondViewControllerDelegate
- (void)secondViewController:(SecondViewController *)sender xValue:(int)value;

@end

And in the m file

- (IBAction)useXPressed:(UIButton *)sender
{
    [self.delegate secondViewController:self xValue:1234]; // 1234 is just for test
}

And then in the firstView I did:

#import "SecondViewController.h"

@interface FirstViewController : UITableViewController <SecondViewControllerDelegate> {

}

@end

And implemented:

- (void) secondViewController:(SecondViewController *)sender xValue:(int)value
{
    [self.navigationController popViewControllerAnimated:YES];
}

Now, the problem is for one in FirstViewController I get the warning that “No definition of protocol “SecondViewControllerDelegate” is found, and for two the delegate method (last piece of code above) does not get invoked at all. Can somebody please tell me what’s wrong?

Answer 1

After this line

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

Add

secondVC.delegate = self;

Also instead of

- (void) secondViewController:(SecondViewController *)sender xValue:(int)value
{
    [self.navigationController popViewControllerAnimated:YES];
}

You should use

- (void) secondViewController:(SecondViewController *)sender xValue:(int)value
{
    [sender popViewControllerAnimated:YES];
}