Question

Possible Duplicate:
Passing model objects from one view controller to another in a navigation stack

I am trying to pass the control between two views in iphone. I have tried this and it works fine when you pass from the first view controller to the second but when i click the second, it blanks out. Why is that so? Any help is appreciated.. Thanks…

Viewcontroller.h

#import <UIKit/UIKit.h>
#import "ViewController2nd.h"

@interface ViewController : UIViewController <SecondViewControllerDelegate>
{
    IBOutlet UILabel *lbl;

}
-(IBAction)passdata:(id)sender;

@end

Viewcontroller.m

#import "ViewController.h"
#import "ViewController2nd.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
-(void) changeLabel:(NSString*)str{
    lbl.text = @"Hello";
}

-(IBAction)passdata:(id)sender{
    ViewController2nd *second = [[ViewController2nd alloc] initWithNibName:nil bundle:nil];
    [self presentViewController:second animated:YES completion:^{ }];
}

@end

ViewController2nd.h

#import <UIKit/UIKit.h>


@protocol SecondViewControllerDelegate <NSObject>
@optional
-(void) changeLabel:(NSString*)str;
@end

@interface ViewController2nd : UIViewController{

    IBOutlet UIButton *bttn;

}

-(IBAction)bttnclicked;
-(IBAction)back:(id)sender;
@end

ViewController2nd.m

#import "ViewController2nd.h"
#import "ViewController.h"

@interface ViewController2nd ()

@end

@implementation ViewController2nd

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

-(IBAction)bttnclicked{

}

-(IBAction)back:(id)sender{
    ViewController *first = [[ViewController alloc] initWithNibName:nil bundle:nil];
    [self presentmodalViewController:first animated:YES completion:^{ }];
}

@end

Am i missing something?

Answer 1

If your requirement is to go to the first view change the back: method like:

-(IBAction)back:(id)sender
 {
     [self dismissViewControllerAnimated:YES completion:NULL];
 }

Don’t display the parentView as the childView of the chilkdViewController. It also makes memory issues and logical issues.

So if you want to go from the childView to parentView, dismiss the childView and never create the parent object and present it there.