Managing the Keyboard with Text field focus in Swift

class MyFavouritesAddNewItemViewController: UIViewController,UITextViewDelegate {

    @IBOutlet weak var firstTextField: UITextField!
    @IBOutlet weak var secondTextField: UITextField!
    @IBOutlet weak var scrollView: UIScrollView!

    override func viewDidLoad() {
        super.viewDidLoad()
        
        firstTextField.delegate = self
        secondTextField.delegate = self
    }

    func textFieldShouldReturn(textField: UITextField) -> Bool {
        textField.resignFirstResponder()
        return true
    }

    override func viewWillAppear(animated:Bool) {
        super.viewWillAppear(animated)
        NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillBeHidden:", name: UIKeyboardWillHideNotification, object: nil)
        NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillShow:"), name: UIKeyboardWillShowNotification, object: nil)
    }
    
    override func viewWillDisappear(animated: Bool) {
        super.viewWillDisappear(animated)
        NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillHideNotification, object: nil)
        NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillShowNotification, object: nil)
    }
    
    var activeField: UITextField?
    
    // Called when the UIKeyboardWillHideNotification is sent
   func keyboardWillBeHidden(aNotification: NSNotification) {
        let contentInsets: UIEdgeInsets = UIEdgeInsetsZero
        self.scrollView.contentInset = contentInsets
        self.scrollView.scrollIndicatorInsets = contentInsets
    }
    
    func textFieldDidBeginEditing(textField: UITextField) {
        activeField = textField
    }
    
    func textFieldDidEndEditing(textField: UITextField) {
        activeField = nil
    }
    
    func keyboardWillShow(aNotification: NSNotification) {
        var info: [NSObject : AnyObject] = aNotification.userInfo!
        let kbSize: CGSize = (info[UIKeyboardFrameEndUserInfoKey]?.CGRectValue.size)!
        let contentInsets: UIEdgeInsets = UIEdgeInsetsMake(0.0, 0.0, kbSize.height, 0.0)
        scrollView.contentInset = contentInsets
        scrollView.scrollIndicatorInsets = contentInsets
        var aRect: CGRect = self.view.frame
        aRect.size.height -= kbSize.height
        if !CGRectContainsPoint(aRect, activeField!.frame.origin) {
            self.scrollView.scrollRectToVisible(activeField!.frame, animated: true)
        }
    }

}