IBOutlet properties nil after custom view loaded from xib

Something strange going on with IBOutlets.

In code I've try to access to this properties, but they are nil. Code:

class CustomKeyboard: UIView {

    @IBOutlet var aButt: UIButton!
    @IBOutlet var oButt: UIButton!

    class func keyboard() -> UIView {
        let nib = UINib(nibName: "CustomKeyboard", bundle: nil)
        return nib.instantiateWithOwner(self, options: nil).first as UIView
    }

    override init() {
        super.init()
        commonInit()
    }

    override init(frame: CGRect) {
        super.init(frame: frame)
        commonInit()
    }

    required init(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        commonInit()
    }

    // MARK: - Private
    private func commonInit() {
        println(aButt)
        // aButt is nil

        aButt = self.viewWithTag(1) as UIButton
        println(aButt)
        // aButt is not nil
    }
}

That's expected, because the IBOutlet(s) are not assigned by the time the initializer is called.

Instead of calling commonInit() in init(coder:), do that in an override of awakeFromNib as follows:

// ...

required init(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
}

override func awakeFromNib() {
    super.awakeFromNib()

    commonInit()
}

// ...