NSString variable available throughout program

I have this line of code:

NSString *dateString = [self.dates objectAtIndex:row];

that gets set when a user selects a row in a picker. I'd like to have this code available everywhere and not just in the picker select area. Other wise I get a "dateString" is undeclared error message of course.

how would i go about doing this?

thanks for any hel开发者_如何学Cp.

---

Why don't you use the singleton design pattern ? To me, it seems to be a cleaner solution that solutions posted above.

VariableStore.m

#import "VariableStore.h"

@implementation VariableStore

@synthesize dateString;

+ (VariableStore *)sharedInstance
{
    static VariableStore *myInstance = nil;

    if (nil == myInstance)
        myInstance  = [[[self class] alloc] init];

    return myInstance;
}
@end

VariableStore.h

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

@interface VariableStore : NSObject
{
    NSString *dateString;
}

+ (VariableStore *)sharedInstance;

@property (nonatomic, retain) NSString *dateString;

@end

AnyClassWhereYouWantToUseYourVariable.h

#import "VariableStore.h"

AnyClassWhereYouWantToUseYourVariable.m

NSLog("dateString = %@", [VariableStore sharedInstance].dateString);

---

A simple, but not very elegant solution is to use NSUserDefaults.

NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];

// saving an NSString
[prefs setObject:@"TextToSave" forKey:@"keyToLookupString"];
[prefs synchronize];

// getting an NSString
NSString *myString = [prefs stringForKey:@"keyToLookupString"];

---

Define as a global variable in your interface file(.h) file. If you want to use in other class as well make the property and synthesize it.

---

Use this code. You can save the entire string. Just create NSString object of

in (YourDelegare.h) file

NSString * dateString;

in (YourDelegare.m) file

  -(void) saveMyState 
 {
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];

[prefs setObject:dateString forKey:@"dateString"];  

[prefs synchronize];
 }


- (void) retrieveMyState
{
//Retrieving

NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
dateString = [prefs stringForKey:@"dateString"];


 }

just call these methods wherever required.

---

Or you can declare that variable in your delegate file.

In yourdelegate.h:

NSString *yourString;

@property (nonatomic, retain) NSString *yourString;

In yourdelegate.m:

@synthesize yourString;

In viewcontrolller.h:

yourdelegate *appDelegate;

In viewcontrolller.m:

appDelegate = [[UIApplication sharedApplication] delegate];  // in viewDidLoad
appDelegate.yourString = [self.dates objectAtIndex:row];  // where ever you need

And, like magic, it's a global variable now.