How to do a log out [iOS] - ios

Question

I have 2 ViewControllers. After login it will move to the next screen. Then one logout button will be appear. After user press log out button it should return to login screen with an empty text field.
How would I do that? I tried all ways, but it doesn't seem to work.
My first ViewController:
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
self.sampleDictionary = #{#"username":#"alex", #"password":#"1234"};
}
- (IBAction)loginTapped
{
if ([self.sampleDictionary[#"password"] isEqualToString:passwordField.text]) {
[self performSegueWithIdentifier:#"ss" sender:self];
} else {
// Alert message
UIAlertController *alertController = [UIAlertController alertControllerWithTitle:#"wrong" message:#"Message" preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction *actionOk = [UIAlertAction actionWithTitle:#"Ok" style:UIAlertActionStyleDefault handler:nil];
[alertController addAction:actionOk];
[self presentViewController:alertController animated:YES completion:nil];
}
}
#end
This is my second ViewController:
- (void)viewDidLoad
{
[super viewDidLoad];
self.navigationItem.hidesBackButton = YES;
}
- (IBAction)logout:(id)sender {
[self dismissViewControllerAnimated:YES completion:nil];
}

Answer 1

In your ViewController remove the text for username and password fields in viewWillAppear.
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
usernameField.text = #"";
passwordField.text = #"";
}

Answer 2

In your second ViewController:
- (void)viewDidLoad
{
[super viewDidLoad];
UIButton *logoutButton = [[UIButton alloc] initWithFrame:CGRectMake(0, 100, 320, 50)];
[logoutButton setTitle:#"Log Out" forState:UIControlStateNormal];
[logoutButton setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
[logoutButton setBackgroundColor:[UIColor blackColor]];
[logoutButton addTarget:self action:#selector(logout) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:logoutButton];
}
- (void)logout
{
[self dismissViewControllerAnimated:YES completion:nil];
}