Passing values from second view to firstView in Xcode - iphone

Question

I have been stuck here.
I have a NSString in Appdelegate. And I have two views called firstview,second view.In first view I have a label and set text from stringvariable which is in Appdelegate .When I click on the button in first view,It goes to the secondview(added the second view to first view as a subview).In second view I have a back button.when I click the back button it is displaying the first view ( Here I am setting the value which is in the appdelegate.And then used this [self.view removeFromSuperview]).The Problem is first view is appearing but label value is not updating.Can any body tell me how to update the Labeltext.Kindly tell me.
Appdelegate.h
#import <UIKit/UIKit.h>
#class FirstView;
#interface AppDelegate : UIResponder <UIApplicationDelegate>
{
NSString *str1;
}
#property (nonatomic,retain) NSString *str1;
#property (strong, nonatomic) UIWindow *window;
#property (strong, nonatomic) ViewController *viewController;
#end
Appdelegate.m
#import "AppDelegate.h"
#import "FirstView.h"
#implementation AppDelegate
#synthesize window = _window;
#synthesize viewController = _viewController;
#synthesize str1;
- (void)dealloc
{
[_window release];
[_viewController release];
[super dealloc];
}
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
// Override point for customization after application launch.
self.viewController = [[[FirsView alloc] initWithNibName:#"FirstView" bundle:nil] autorelease];
self.str1 = #"view1";
self.window.rootViewController = self.viewController;
[self.window makeKeyAndVisible];
return YES;
}
FirstView.h
#import <UIKit/UIKit.h>
#import "secondView.h"
#interface FirstView : UIViewController
{
IBOutlet UILabel *btn;
secondView *cont;
}
-(IBAction)gotoView2:(id)sender;
#end
FirstView.m
#import "FirstView.h"
-(IBAction)gotoView2:(id)sender
{
cont = [[secondView alloc] initWithNibName:#"secondView" bundle:nil];
[self.view addSubview:cont.view];
}
#pragma mark - View lifecycle
- (void)viewDidLoad
{
[super viewDidLoad];
AppDelegate *del = [[UIApplication sharedApplication] delegate];
[btn setTitle:del.str1];
}
**SecondView.h**
#import <UIKit/UIKit.h>
#interface SecondView : UIViewController
{
}
-(IBAction)goBack:(id)sender;
#end
SecondView
#import "SecondView.h"
#import "AppDelegate.h"
#implementation SecondView
-(IBAction)gotoView1:(id)sender
{
AppDelegate *del = [[UIApplication sharedApplication] delegate];
[del setStr1:#"Home"];
[self.view removeFromSuperView];
}

Answer 1

There is a pattern how to do such things. You should define a protocol like this:
#protocol FirstViewDelegate <NSObject>
- (void)didDismissSecondView;
#end
Your first view should conform to this protocol:
#interface FirstView: UIViewController <FirstViewDelegate> {
...
in its implementation add function didDismissSecondView:
- (void) didDismissSecondView
{
AppDelegate *del = [[UIApplication sharedApplication] delegate];
[btn setTitle:del.str1];
}
Your second view has to have a property
#interface SecondView : UIViewController
{
id<FirstViewDeledate> delegate;
}
#property (nonatomic, retain) id<FirstViewDeledate> delegate;
When you show your second view from the first view set its delegate to self of first view
in your function:
-(IBAction)gotoView2:(id)sender
{
SecondView *aView = [[SecondView alloc] init] // or whatever
...//other initialization code
aView.delegate = self;
... // show it
}
and before you dismiss the second view:
-(IBAction)gotoView1:(id)sender
{
AppDelegate *del = [[UIApplication sharedApplication] delegate];
[del setStr1:#"Home"];
[self.delegate didDismissSecondView];
[self.view removeFromSuperView];
}
And you done.
A bit long, but works.