iPhone SDK中的NSUserDefault疑问

Question

I have an application that backs up and restores notes to Evernote. Things are working well, but I'm having trouble when logging out and logging back in as a different Username and Password combination.

The first time I share my note with the initial values for Username/Password, it works correctly. However, logging out and back in with a different Username/Password posts my notes to the original account.

I have a Singleton class which writes the username/password to the NSUserDefaults and SFHFKeychainUtils. Here is the login method:

 NSError *error = nil;
            NSString *unameever = _txtevernoteUsername.text;

            NSString *pwdever   = _txtevernotepasswrd.text;
            [[NSUserDefaults standardUserDefaults] setObject:unameever forKey:@"usernameevernote"];
            [[NSUserDefaults standardUserDefaults]synchronize];
            [[NSUserDefaults standardUserDefaults] setObject:pwdever forKey:@"passwrdevernote"];
            [[NSUserDefaults standardUserDefaults]synchronize];
            BOOL flag = [SFHFKeychainUtils storeUsername:unameever andPassword:pwdever forServiceName:@"mybibleappever" updateExisting:TRUE error:&error];

Here is the connect method for sending the username/password:

- (void) connect {
  NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];

        //Checks if there is a saved User Name    
        if([defaults objectForKey:@"usernameevernote"]&&[defaults objectForKey:@"passwrdevernote"])
        {

            NSString *usernameever = [defaults objectForKey:@"usernameevernote"];
             NSString *passwever = [defaults objectForKey:@"passwrdevernote"];

        // Returned result from the Evernote servers after authentication
        EDAMAuthenticationResult* authResult =[userStore authenticate:usernameever :passwever : consumerKey :consumerSecret];

Here is the log out method:

    NSError *error = nil;
                NSString *usernameever = [[NSUserDefaults standardUserDefaults] objectForKey:@"usernameevernote"];
                BOOL flag = [SFHFKeychainUtils deleteItemForUsername:usernameever andServiceName:@"mybibleappever" error:&error];
[[NSUserDefaults standardUserDefaults] removeObjectForKey:@"usernameevernote"]; 

any problem with my code..please help me to do this.

Answer 1

Here are some tips:

• You only have to call [[NSUserDefaults standardUserDefaults]synchronize] once, at the end of setting your values.

• It doesn't seem like you're deleting the standardUserDefaults value in the logout, which might be why you are getting the same login/user persisting.

• From the code you posted it looks like you're storing but never using the value in SFHFKeychainUtils