Best way to pass variables between views - iphone

Question

I am very new to xcode & Objective-C (having come from PHP) i have started to play around and am finding it very hard to pass variables between views this is what i have so far:
Game_info.h
#import <UIKit/UIKit.h>
#interface Game_Info : UIViewController {
IBOutlet UITextField *groupName;
IBOutlet UISegmentedControl *gameType;
}
#property (nonatomic,retain) IBOutlet UITextField *groupName;
- (IBAction) GameTypePicker;
- (IBAction) KeyboardHide;
- (IBAction) BackBTN;
- (IBAction) NextBTN;
#end
Game_Info.m
#import "I_Dare_YouViewController.h"
#import "Game_Info.h"
#import "Game_TDoR.h"
#implementation Game_Info
#synthesize groupName;
// Next Button
-(IBAction) NextBTN{
if ([groupName.text length] == 0) {
// Alert
UIAlertView *alert = [[UIAlertView alloc]
initWithTitle:#"Group Name"
message:#"Please enter a group name"
delegate:self
cancelButtonTitle:#"OK"
otherButtonTitles:nil
];
[alert show];
[alert release];
}else if([groupName.text length] < 3){
// Alert
UIAlertView *alert = [[UIAlertView alloc]
initWithTitle:#"Group Name"
message:#"Please enter a name longer than 3 characters"
delegate:self
cancelButtonTitle:#"OK"
otherButtonTitles:nil
];
[alert show];
[alert release];
}else{
Game_TDoR *screen = [[Game_TDoR alloc] initWithNibName:nil bundle:nil];
screen.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
[self presentModalViewController:screen animated:YES];
[screen release];
Game_TDoR *screen1 = [[Game_TDoR alloc] initWithNibName:nil bundle:nil];
NSLog(#"Game_Info: %#",self.groupName.text);
screen1.groupNameText = self.groupName.text;
[self presentModalViewController:screen1 animated:YES];
[screen1 release];
}
}
Then in another view / .h / .m file i am trying to get to the 'groupName' property.
Game_TDoR.m
#import "I_Dare_YouViewController.h"
#import "Game_Info.h"
#import "Game_TDoR.h"
#implementation Game_TDoR
#synthesize groupNameText,Testlbl;
- (void)viewDidLoad
{
NSLog(#"Game_TDoR: %#",self.groupNameText);
NSString *msg = [[NSString alloc] initWithFormat:#"Hello, %#",[self.groupNameText capitalizedString]];
[Testlbl setText:msg];
[msg release];
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
}
So what i am trying to do is on the first view page (Game_info) there is an input text box and im trying to pass that to a label on another view page (Game_TDoR)
This is what comes out in the NSLog (note that the second page (Game_TDoR) comes out first in the log.
2011-07-17 00:25:34.765 I Dare You[3941:207] Game_TDoR: (null)
2011-07-17 00:25:34.774 I Dare You[3941:207] Game_Info: Name
Problem solved:
On the next button i needed to add the variable before i moved page (not the other way around - silly noobish thing to do...)
Game_TDoR *screen1 = [[Game_TDoR alloc] initWithNibName:nil bundle:nil];
NSLog(#"Game_Info: %#",self.groupName.text);
screen1.groupNameText = self.groupName.text;
[self presentModalViewController:screen1 animated:YES];
[screen1 release];
Game_TDoR *screen = [[Game_TDoR alloc] initWithNibName:nil bundle:nil];
screen.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
[self presentModalViewController:screen animated:YES];
[screen release];

Answer 1

If you need to pass the value of groupName.text from the Game_Info view controller to the Game_TDoR view controller, which is presented modally by the former, you can declare a property in Game_TDoR to hold the value:
1) Declare a NSString property in Game_TDoR #interface block:
#property (nonatomic,copy) NSString *groupNameText;
(Remember to synthesize or implement the accessor methods in the implementation block)
2) In NextBTN action, after you initialize your Game_TDoR instance, set the property:
Game_TDoR *screen = [[Game_TDoR alloc] init...];
screen.groupNameText = self.groupName.text;

Answer 2

Merely including the header file will not make the variable available. You are only including the definition of the class (class is for PHP what #interface is for Obj-C) You have to instantiate Game_Info and access the variable via the instance of Game_Info.

Answer 3

groupName is a member (ivar) of Game_Info. Its default visibility is #protected, so any classes outside Game_Info can't access it, unless they derive from Game_Info. To make groupName accessible, you can either create a property that exposes it, or you can make it #public. How this is done is documented in the vast documentation for Xcode.
But groupName, being an ivar (instance variable) of an object, only exists if there is in fact an instance of the Game_Info. I assume you have some globally accessible instance of Game_Info in your program, let's call it globalGameInfo. Now you can access its groupName using
UITextField *gName = [globalGameInfo groupName];

Answer 4

Take this in .h file in SecondViewController
NSString *strABC;
Make below function in SecondViewController.m
-(void)setString:(NSString *)strEntered{
strABC=strEntered;
}
Now In First view controller do like this:
SecondViewController.m *objSecond = [[SecondViewController.m] initwithNibName:#"secondView.xib" bundle:nil];
[objSecond setString:#"Comment Controller"];
[self.navigationController pushViewController:objSecond animated:YES];
[objSecond release];
Now, In secondViewController viewWillAppear Method write this.
-(void)viewWillAppear:(BOOL)animated{
lblUserInput.text = strABC;
}
Please check spelling mistakes as I hand written this. Hope this help.
If you are not using navigationContoller then you can do something like this.
SecondViewControler *objSecond = [[SecondViewController] initwithNibName:#"secondview.xib" bundle:nil];
[objSecond setUserInput:txtUserInput.text];
[objSecond viewWillAppear:YES];
[self.view addSubview:objSecond];
[objSecond release];