Question

#pragma mark SA_OAuthTwitterControllerDelegate
- (void) OAuthTwitterController: (SA_OAuthTwitterController *) controller authenticatedWithUsername: (NSString *) username {
    NSLog(@"Authenicated for %@", username);
    [_btnTwitter setTitle:username forState:UIControlStateNormal];
}

I have this code for displaying username for twitter ,and it works well,but when i navigate to another page and came back the title username of the button disappears,i know we have to set a NSUserDefault value in viewwillapper for checking the username exists or not.But i didn’t know how to handle the nSUserDefault,if anyone have an idea to solve this issue please help me.
Thanks in advance.
EDIT:

- (void)viewWillAppear:(BOOL)animated{
    //Sets up the NSUserDefaults
    //Sets up the NSUserDefaults
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];

    //Checks if there is a saved User Name    
    if([defaults objectForKey:@"kTwitterUserName"])
        NSString *username = [defaults objectForKey:@"kTwitterUserName"];
      [_btnTwitter setTitle:username forState:UIControlStateNormal];
    else
    {

    }

this is how my viewwillappear lokks
and

- (void) OAuthTwitterController: (SA_OAuthTwitterController *) controller authenticatedWithUsername: (NSString *) username {
    NSLog(@"Authenicated for %@", username);
    [_btnTwitter setTitle:username forState:UIControlStateNormal];
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    [defaults setObject:username forKey:@"kTwitterUserName"];
    [defaults synchronize];
    }

this is how my twitermethod looks like

Answer 1

NSUserDefaults are very simple to work with. They are kind of like a dictionary, you set an object and a key. So to do what your trying to do, you can use something like the following:

//This just sets up the defaults - similar to allocating a dictionary
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];

Then to set an object in your defaults, you set an object/key pair like this:

[defaults setObject:username forKey:@"kTwitterUserName"];

It is important to call this method at some point: [defaults synchronize];. This explicitly saves the defaults. So you might as well do it immediately after you set the username key.

Then to read the saved username:

 NSString *username = [defaults objectForKey:@"kTwitterUserName"];

Your oAuth Method should look like this:

- (void) OAuthTwitterController: (SA_OAuthTwitterController *) controller authenticatedWithUsername: (NSString *) username {
     //Any thing else you want to do - NSLogs, etc.

     NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
     [defaults setObject:username forKey:@"kTwitterUserName"];
     [defaults synchronize];
}

So your viewWillAppear will look something like this:

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];

    //Sets up the NSUserDefaults
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];

    //Checks if there is a saved User Name    
     if([defaults objectForKey:@"kTwitterUserName"]) {
         NSString *username = [defaults objectForKey:@"kTwitterUserName"];
    } else
        //Do something else because there is no saved username
        NSLog(@"no username saved");
}

Let me know in a comment if you need any clarification.