无法将WKWebView加载到containerView中

Question

我正在尝试在容器视图中加载一个Web视图，该视图基本上是主视图中的UIView。但不管怎么说它没有加载。

var urlString : String!
var termsAndConditionsWebView : WKWebView!

@IBOutlet var containerView: UIView!
override func loadView() {
    super.loadView()
    //self.termsAndConditionsWebView.frame = containerView.frame
    //self.termsAndConditionsWebView.sizeToFit()
    self.termsAndConditionsWebView = WKWebView()
    containerView = termsAndConditionsWebView
}


override func viewDidLoad() {
    super.viewDidLoad()

    let url = NSURL(string: "https://www.google.com.sg")
    let request = NSURLRequest(URL: url!)
    termsAndConditionsWebView.loadRequest(request)
}