在SWIFT 3.1

Question

func cubeTransition(label label:UILabel, text: String, direction:AnimationDirection) {

    //1
    let auxLabel = UILabel(frame: label.frame)

    auxLabel.text = text
    auxLabel.font = label.font
    auxLabel.textAlignment = label.textAlignment
    auxLabel.textColor = label.textColor
    auxLabel.backgroundColor = label.backgroundColor

    //2
    let auxLabelOffset = CGFloat(direction.rawValue) * label.frame.size.height/2.0

    auxLabel.transform = CGAffineTransform(scaleX: 1.0, y: 0.1).concatenating( CGAffineTransform(translationX: 0.0, y: auxLabelOffset))

    label.superview!.addSubview(auxLabel)

    //3
    UIView.animate(withDuration: 0.5, delay: 0.0, options: .curveEaseOut, animations: {


        auxLabel.transform = .identity

        label.transform = CGAffineTransform(scaleX: 1.0, y: 0.1).concatenating( CGAffineTransform(translationX: 0.0, y: -auxLabelOffset))

    }, completion: {_ in

        label.text = auxLabel.text
        label.transform = .identity
        auxLabel.removeFromSuperview()

    })
}

此示例中有一行代码，即“auxLabel.transform = .identity”这是什么意思？我很困惑，提前谢谢。