Swift - If statement not working as it should

I'm trying to animate an UIButton once two textsfields have had text entered. The button animates even if there is no text entered. I thought maybe it was an issue with there being placeholder text, but that has no effect. I have tried != "" as well as != nil

Here's my code

    override func viewDidLoad() {
    super.viewDidLoad()

    self.title = ""

    textFieldConfig()
    loginButtonConfig("LOG IN")
}

func loginButtonConfig(title:String) {
    let frameWidth = self.view.frame.width
    let frameHeight = self.view.frame.height

    var button = UIButton()
    button.frame = CGRect(x: 0, y: 300, width: 0, height: 50)
    button.bounds = CGRect(x: 0, y: 0, width: 0, height: 50)
    button.backgroundColor = UIColor(red: 24.0/255.0, green: 198.0/255.0, blue: 152.0/255.0, alpha: 1.0)
    button.setTitle(title, forState: .Normal)
    button.titleLabel?.textAlignment = NSTextAlignment.Center
    self.view.addSubview(button)

    //WHY ISN'T THE IF STATEMENT WORKING AS IT SHOULD???
    if self.userTextField.text != nil && self.passwordTextField.text != nil {
       UIView.animateWithDuration(1.0, animations: { () -> Void in
        button.frame = CGRect(x: 0, y: 300, width: frameWidth, height: 50)
        button.bounds = CGRect(x: 0, y: 0, width: frameWidth, height: 50)
       })
    }
}

Any help would be appreciated. Thanks :)