string -> NSURL -> NSURLRequest -> webView.loadRequest

    @IBOutlet weak var textField: UITextField!
    @IBOutlet weak var webView: UIWebView!
    @IBOutlet weak var backButton: UIBarButtonItem!
    @IBOutlet weak var forwardButton: UIBarButtonItem!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // string -> NSURL -> NSURLRequest -> webView.loadRequest
        let startUrl = "http://hogehoge.com"
        if let url = NSURL(string: startUrl){
            let urlRequest = NSURLRequest(URL: url)
            self.webView.loadRequest(urlRequest)
        }
        
    }