AutoLayout後のframeを取得
override func viewDidLoad() {
    super.viewDidLoad()
    let width:CGFloat = self.someView.frame.size.width//AutoLayout前の値が取得できる
}
override func viewDidAppear(animated: Bool) {
    super.viewDidAppear(animated)
    let width:CGFloat = self.someView.frame.size.width//AutoLayout後の値が取得できる
}