uiwebview – 简单的Swift WebView无法正常工作(Xcode 6 Beta 3)

import UIKit

class ViewController: UIViewController {

@IBOutlet var webview: UIWebView

var urlpath = "http://www.google.de"

func loadAddressURL(){
    let requesturl = NSURL(String: urlpath)
    let request = NSURLrequest(URL: requesturl)
    webview.loadrequest(request)
}

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view,typically from a nib.
    loadAddressURL()
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}


}

错误：

Fatal error: unexpectedly found nil while unwrapping an Optional value
(lldb)
self    uiwebview.ViewController    0x7987fc70  0x7987fc70
request NSURLrequest *  0x78ebfc40  0x78ebfc40
requesturl  NSURL * ""  0x78ec0040