Swift1.2→Swift2.0に移行した時に出たsupportedInterfaceOrientations()のエラーについて

Swift1.2で画面の向きを固定する関数にエラーが！！

Swift

// Swift 1.2
override func supportedInterfaceOrientations() -> Int {
    let orientation = Int(UIInterfaceOrientationMask.Portrait.rawValue | UIInterfaceOrientationMask.PortraitUpsideDown.rawValue)
    return Int(UIInterfaceOrientationMask.All.rawValue)
}

Swift

Error: Method does not override any method from its superclass

これでなんとか

Swift

// Swift 2
override func supportedInterfaceOrientations() -> UIInterfaceOrientationMask {
    let orientation: UIInterfaceOrientationMask = [UIInterfaceOrientationMask.Portrait, UIInterfaceOrientationMask.PortraitUpsideDown]
    return orientation
}