Variable suddenly removed

Question

I know the title may sound a little weird, but the same goes for the problem.

I've been testing my app on the simulator almost the entire time in development, I did test it once in a while on a real device just to make sure. But now that I'm close to finishing a problem came up.

Whenever I preform a login, my entire app crashes saying the username and password variables are deallocated ...

Here's the flow of my application:

When opening the app, it checks if the username and password was saved or note

- (void)checkIfPreviouslyLoggedIn:(BOOL)didLogin andLogin:(BOOL)doLogin {
     // some logic to get it out of the keychain
     NSLog(@"checkIfPreviouslyLggedIn: ACCOUNT %@ / %@", tmpUsername, tmpPassword);

     // RETURN: checkIfPreviouslyLggedIn: ACCOUNT  /
}

Nothing was saved before, no big deal, the user will just input the account and press login

- (void)loginWithUsername:(NSString *)username andPassword:(NSString *)password {
      NSLog(@"loginWithUsername: ACCOUNT %@ / %@", username, password);
      // RETURN: loginWithUsername: ACCOUNT testUser / password

      // save it for later use
      _username = username;
      _password = password;

      NSLog(@"loginWithUsername: ACCOUNT %@ / %@", _username, _password);
      // RETURN: loginWithUsername: ACCOUNT testUser / password

      // Attach a notification handler
      [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(loginCheck:) name:@"LoginCheck" object:nil];

      // call the web API
      [self doRequestFromLocation:@"/groups" withPostType:@"GET" andData:nil whichTriggersNotification:@"LoginCheck"];
}

Cool, the username and password are nicely logged, so far so good, the doRequestFromLocation is basically a queue type thing, I can send as many requests as I want and it will handle them one by one

- (void)doRequestFromLocation:(NSString *)location withPostType:(NSString *)type andData:(NSData *)data whichTriggersNotification:(NSString *)notification {
      NSLog(@"doRequestFromLocation: ACCOUNT %@ / %@", _username, _password);
      // RETURN: doRequestFromLocation: ACCOUNT testUser / password
}

It then goes to a doRequest method, which does the actual data request, again, I log my username there and it's returning the correct one.

NSLog(@"doRequest: ACCOUNT %@ / %@", _username, _password);

It's after this that everything goes horribly wrong, when the request is completed, loginCheck() is called

- (void)loginCheck:(NSNotification *)notification {
    NSLog(@"loginCheck: ACCOUNT %@ / %@", _username, _password);
}

In here my _username and _password are deallocated, even right before the actual call I check the username and password and they are still fine.

So somehow (magically) those 2 variables got deallocated without any reason. Note that _username and _password is ONLY set in loginWithUsername, they don't change anywhere in my application.

2012-06-04 13:33:28.001 coop[5060:707] * -[CFString respondsToSelector:]: message sent to deallocated instance 0x1099fc40 2012-06-04 13:33:28.648 coop[5060:707] * -[CFString _cfTypeID]: message sent to deallocated instance 0x1099fc40

What could have caused this, I added multiple breakpoints, only to realize that somewhere between the call and the loginCheck() they disappear.

score 1 · Accepted Answer · edited Jun 04 '12 at 05:50

1

the problem is here:

 // save it for later use
      _username = username;
      _password = password;

your variables _username and _password are not retained that's why they are getting autoreleased.

either in NON-ARC case, declare them as @property(retain) and for ARC, @property(strong) use :

self._username = username;
self._password = password;

now you own the ownership of the memory and now you have to release it whenever you're done.

edited Jun 04 '12 at 05:50

Ilanchezhian

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answered Jun 04 '12 at 05:46

Saurabh Passolia

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That was indeed the problem, is this something the simulator handles differently? I never had any problems with it on there. – woutr_be Jun 04 '12 at 05:59

score 1 · Answer 2 · answered Jun 04 '12 at 05:56

Please check how did you declared your properties (_username and _password) in your header file. if it is not declared as

@property (nonatomic, retain) NSString * _username;
@property (nonatomic, retain) NSString * _password;

then your properties would get autoreleased. So later when you try to access this properties you get message that they deallocated.

Also, when you declare your variables as properties in header file, do access them with "self.".

Please deallocate your properties only after you are done with them, no further access to this properties is required.

Please let me know if any need any more help on the same

Variable suddenly removed

2 Answers2