Objective-C remove UIButton from Superview

Question

I have this UIButton defined in my .h file:

@property (nonatomic,strong) UIButton *loginButton;

- (void)LoginButtonPressed:(UIButton *)sender;

and have it created in my .m file:

@synthesize loginButton;

loginButton = [UIButton buttonWithType:UIButtonTypeCustom];
[loginButton setFrame:CGRectMake(150.0f, 131.0f, 105.0f, 35.0f)];
[loginButton setBackgroundImage:[UIImage imageNamed:@"black_button.png"] forState:UIControlStateNormal];
[loginButton setTitle:@"Login" forState:UIControlStateNormal];
[loginButton setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
[loginButton addTarget:self action:@selector(LoginButtonPressed:) forControlEvents:UIControlEventTouchUpInside];

- (void)LoginButtonPressed:(UIButton *)sender
{
    [self CreateActivityIndicator];
    [self performSelector:@selector(Login) withObject:nil afterDelay:0.5];

}

and I have a method called login and on login I want to remove the login button from superview.

[self.loginButton removeFromSuperview];

but all of a sudden (as of yesterday) my app started crashing and throwing an error on this line:

@property (nonatomic,strong) UIButton *loginButton;

Thread 1: EXC_BAD_ACCESS(code=1, address0x10000010)

Why is this happening? and how can I fix it? I did change my login method around yesterday to use AFNetworking, could that be it?

Just in case, here is my full method:

- (void)Login
{
    NSString *rawString = [self.idTextField text];
    NSCharacterSet *whitespace = [NSCharacterSet whitespaceAndNewlineCharacterSet];
    [self.idTextField setText:[rawString stringByTrimmingCharactersInSet:whitespace]];

    [userName UserLogin:self.idTextField.text andPassWordExists:self.passwordTextField.text completionHandler:^(id responseObject, NSError *error) {
        if (responseObject) {
            [self.idTextField removeFromSuperview];
            [self.passwordTextField removeFromSuperview];
            [self.loginButton removeFromSuperview];
            self.idTextField = nil;
            self.passwordTextField = nil;
            self.loginButton = nil;
            [self CreateMenu];
        }else{
            [self CustomAlert:@"Sorry Login Failed, User and/or Passsword Incorrect"];
        }
    }];

    [indicatorView stopAnimating];
    [indicatorView removeFromSuperview];
    indicatorView = nil;
    [loadingView removeFromSuperview];
    loadingView = nil;

}

and here is what is triggering it:

-(void)UserLogin:(NSString *)user andPassWordExists:(NSString *)password completionHandler:(void (^)(NSArray *resultsObject, NSError *error))completionHandler
{


   NSURL *url = [NSURL URLWithString:kIP];
   NSURLRequest *request = [NSURLRequest requestWithURL:url];

    AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc]
                                         initWithRequest:request];


    NSURLCredential *credential = [NSURLCredential
                                   credentialWithUser:user
                                   password:password
                                   persistence:NSURLCredentialPersistenceForSession];

    [operation setCredential:credential];

    [[NSOperationQueue mainQueue] addOperation:operation];

    [operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {

        if (completionHandler) {
            completionHandler(responseObject, nil);
        }

    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {

        if (completionHandler) {
            completionHandler(nil, error);
        }

    }];

    [operation start];
}

Here is how my button is getting added to the view, along with the 2 text items:

//add all controls to the loginView
        [loginMenuView addSubview:self.idTextField];
        [loginMenuView addSubview:self.passwordTextField];
        [loginMenuView addSubview:self.loginButton];

UPDATE

I was able to resolve this issue by doing the following:

taking out self.loginButton = nil; from my Login Method, so it looks like this:

- (void)Login
{
    NSString *rawString = [self.idTextField text];
    NSCharacterSet *whitespace = [NSCharacterSet whitespaceAndNewlineCharacterSet];
    [self.idTextField setText:[rawString stringByTrimmingCharactersInSet:whitespace]];


    [userName UserLogin:self.idTextField.text andPassWordExists:self.passwordTextField.text completionHandler:^(id responseObject, NSError *error) {
        if (responseObject) {

                [self.idTextField removeFromSuperview];
                [self.passwordTextField removeFromSuperview];
                [self.loginButton removeFromSuperview];
                self.idTextField = nil;
                self.passwordTextField = nil;
                //self.loginButton = nil;


                [self CreateMenu];



                [indicatorView stopAnimating];
                [indicatorView removeFromSuperview];
                indicatorView = nil;
                [loadingView removeFromSuperview];
                loadingView = nil;
        }else{


            [self CustomAlert:@"Sorry Login Failed, User and/or Passsword Incorrect"];

            [indicatorView stopAnimating];
            [indicatorView removeFromSuperview];
            indicatorView = nil;
            [loadingView removeFromSuperview];
            loadingView = nil;

        }
    }];

}

and taking out [self.loginButton removeFromSuperview]; and self.loginButton = nil; from my viewWillDisappear method like so:

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    userName = nil;
    [[NSNotificationCenter defaultCenter]removeObserver:self];
    [self.idTextField removeFromSuperview];
    [self.passwordTextField removeFromSuperview];
    //[self.loginButton removeFromSuperview];
    [self.menu removeFromSuperview];
    [logoutButton removeFromSuperview];
    //set every control to nil
    self.idTextField = nil;
    self.passwordTextField = nil;
    //self.loginButton = nil;
    self.menu = nil;
    menuItems = nil;
    textfieldNavigatorView = nil;
}

this has solved my problem, I just want to know if this is the best solution.

Answer 1

What I think is happening is that your loginButton is tied to your indicatorView or loadingView.

Since you're using a completion handler, the code inside of it is going to run asynchronously. That means that your

indicatorView = nil 

or your

loadingView = nil

is being triggered before your loginButton is being removed. If loginButton is a subview of one of those views, nothing has reference to it anymore, thus you get a BAD_ACCESS. Make sure you put the last 5 lines of code (the ones that deal with loadingView and indicatorView) inside of your completion handler like so:

- (void)Login
{
NSString *rawString = [self.idTextField text];
NSCharacterSet *whitespace = [NSCharacterSet whitespaceAndNewlineCharacterSet];
[self.idTextField setText:[rawString stringByTrimmingCharactersInSet:whitespace]];

[userName UserLogin:self.idTextField.text andPassWordExists:self.passwordTextField.text completionHandler:^(id responseObject, NSError *error) {
    if (responseObject) {


        [self.idTextField removeFromSuperview];
        [self.passwordTextField removeFromSuperview];
        //access the loginButton while it still has reference
        [self.loginButton removeFromSuperview];
        self.idTextField = nil;
        self.passwordTextField = nil;
        //access the loginButton while it still has reference
        self.loginButton = nil;

        //Then remove these views
        [indicatorView stopAnimating];
        [indicatorView removeFromSuperview];
        indicatorView = nil;
        [loadingView removeFromSuperview];
        loadingView = nil;

        [self CreateMenu];
    }else{
        [self CustomAlert:@"Sorry Login Failed, User and/or Passsword Incorrect"];
    }
}];

}