iPhone application accessing data values from different classes - iphone

Question

I have 4 classes i.e views in my application. Class A, having variable a and b.
After clicking on button which is on view A of class A it leads to class B, which is table view controller. Then class B leads to class C. then class C leads to class D.
Now i want to access values of a and b of class A into class D. I tried it with NSNotification but not succeeded.
Please suggest.
I tried with NSNotification:
i tried with NSNotification like Class A---
-(IBAction) selectButton:(id) sender{
NSString * a = [NSString stringWithFormat:#"Manjinder singh"];
NSDictionary * dict = [NSDictionary dictionaryWithObject:a forKey:#"1"];
[[NSNotificationCenter defaultCenter] postNotificationName:#"sendMessage" object:self userInfo:dict];
}
Then Class D----
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(sendMessage:) name:#"sendMessage" object:nil];
}
return self;
}
-(void)sendMessage:(NSNotification *)notification{
A *dil=[[A alloc] init];
nslog(#"dil.a");
NSLog(#"USERINFO:MyUserInfo (its a dictionary):%#",[[notification userInfo] valueForKey:#"1"]);
}
This is the rendom try but basically i want to show variable a and b of class A into class D.
Update:------------
MyCoolViewController.h// a class where data send from
#protocol MyCoolViewDelegate;
#interface MyCoolViewController : UIViewController {
id <MyCoolViewDelegate> delegate;//
}
#property (nonatomic, assign) id delegate;//
#end
#protocol MyCoolViewDelegate <NSObject>//
-(void)sendAStringToAnotherView:(NSString*)string;
#end
MyCoolViewController.m
-(void)viewDidLoad{
[delegate sendAStringToAnotherView:#"this is a string"];
}
firstViewController.m //a class where data sent
-(void)viewDidLoad{
MyCoolViewController *myViewControllerPointer=[[MyCoolViewController alloc] init];
myViewControllerPointer.delegate = self;//
}
-(void)sendAStringToAnotherView:(NSString*)string
{
//displays the string as console output
NSLog(#"plzzzzzz show data",string);
}
value of string is not passed to this class because it is not showing in NSLog output.
UPDATED 2---
MyCoolViewController.m
#import “MyCoolViewController.h”
#import "firstViewController.h"
#implementation MyCoolViewController
#synthesize label1,sttr;
#synthesize delegate;//
-(IBAction) selectButton:(id) sender{
if (curri==nil) {
curri=[[CurrancyViewController alloc] initWithNibName:nil bundle:nil];
[self.navigationController pushViewController:curri animated:YES];
}
curri=nil;
//CHECK ThIS [curri release];
}
- (void)viewDidLoad
{
[delegate sendAStringToAnotherView:#"this is a string"];
self.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:#"background1.png"]];
[super viewDidLoad];
}
- (BOOL)shouldAutorotateToInterfaceOrientation: (UIInterfaceOrientation)interfaceOrientation
{
// Return YES for supported orientations
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
#end

Answer 1

Can you give more context about what specifically you are trying to achieve? It sounds like you want to pass data between several UIViewControllers. Here is how to set up a delegate for one of your view controllers:
#import <UIKit/UIKit.h>
#protocol MyCoolViewControllerDelegate;
#interface MyCoolViewController : UIViewController {
id <MyCoolViewControllerDelegate> delegate;
}
#property (nonatomic, assign) id delegate;
#end
#protocol MyCoolViewControllerDelegate <NSObject>
-(void)sendAStringToAnotherView:(NSString*)string;
#end
Then you will should synthesize the delegate
#synthesize delegate;
and then when you want to pass data to, lets say a parent view, call this function:
[delegate sendAStringToAnotherView:#"this is a string"];
In the other view controller, wherever you instantiated the instance of this UIViewController, you need to set that self as the delegate;
myViewControllerPointer.delegate = self;
and then implement the delegate function in the parent view controller.
-(void)sendAStringToAnotherView:(NSString*)string
{
//displays the string as console output
NSLog(string);
}
The fact that you need communicate between views like this could possibly mean that there is a more efficient means of structuring your app. Can't say for sure without more info.
Try and use this template to add a delegate to your own app.

Answer 2

You could use delegation here
D would become the delegate of A, and when you click the button, A sends a message to D with the variables as arguments and D responds by performing a method.