Cacher is the code snippet organizer for pro developers

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        NotificationCenter.default.addObserver(self, selector: #selector(self.keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(self.keyboardWillHide), name: UIResponder.keyboardWillHideNotification, object: nil)
    }
    
    
    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        NotificationCenter.default.removeObserver(self)
    }



//MARK: Keyboard
    
    @objc func keyboardWillShow(notification: NSNotification) {
        
        if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
            let deviceIdiom = UIScreen.main.traitCollection.userInterfaceIdiom
            
            if (deviceIdiom != .pad) {
                if self.view.frame.origin.y == 0{
                    self.view.frame.origin.y -= (keyboardSize.height - 60)
                }
            }
        }
    }
    
    @objc func keyboardWillHide(notification: NSNotification) {
        
        if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
            let deviceIdiom = UIScreen.main.traitCollection.userInterfaceIdiom
            
            if (deviceIdiom != .pad) {
                if self.view.frame.origin.y != 0{
                    self.view.frame.origin.y += (keyboardSize.height - 60)
                }
            }
        }
    }

0) La view de pantalla debe tener una view dentro que es la que se desplazará
0.5) El ViewController debe heredar de TextViewController (clase propia) en .h
@interface LOCreateAccountViewController : TextViewController

1) Crear una constraint a bottom y top (con distancia 0) entre la view nueva y la propia de la pantalla
2) Enlazarla en el .m (dentro de interface)
3) Controlar el campo RETURN KEY de los TextFields
4) Añadir el código:

-(void)keyboardWillShow:(NSNotification *)notification{
    NSDictionary *info = [notification userInfo];
    NSValue *kbFrame = [info objectForKey:UIKeyboardFrameEndUserInfoKey];
    
    CGRect keyboardFrame = [kbFrame CGRectValue];
    
    CGRect finalKeyboardFrame = [self.view convertRect:keyboardFrame fromView:self.view.window];
    
    int kbHeight = finalKeyboardFrame.size.height;
    
    int height = kbHeight;

    int offsetY = self.currentField.frame.origin.y+ (int) self.currentField.frame.size.height;
    int vHeight = self.view.frame.size.height;
    
    if(vHeight - offsetY < height){
        
        self.cBottom.constant = abs(vHeight - height - offsetY  - 10);
        self.cContentTop.constant = 20-self.cBottom.constant;

    }
    
}

-(void)keyboardWillHide:(NSNotification *)notification{
    [super keyboardWillHide:notification];
    self.cContentBottom.constant = 0;
    self.cContentTop.constant = 20;
}

- (BOOL)textFieldShouldReturn:(UITextField *)textField {
    
    if ([textField isEqual:self.textFieldEmail]) {
        [textField resignFirstResponder];
        [self.textFieldPassword becomeFirstResponder];
    }
    if ([textField isEqual:self.textFieldPassword]) {
        [textField resignFirstResponder];
    }
    
    return YES;
}