gistfile1.swift

func webView(webView: UIWebView, shouldStartLoadWithRequest request: NSURLRequest, navigationType: UIWebViewNavigationType) -> Bool {
  guard let url = request.URL else {
    return true
  }
  if url.scheme.rangeOfString("^https?", options: .RegularExpressionSearch) != nil {
    return true
  }
  if !UIApplication.sharedApplication().canOpenURL(url) {
    // iOS9でInfo.plistに登録してないとfalseになるのでここに来る
    return false
  }
  let ac = UIAlertController(title: "", message: "Open \(url.absoluteString)?", preferredStyle: .Alert)
  ac.addAction(UIAlertAction(title: "No", style: .Cancel, handler: nil))
  ac.addAction(UIAlertAction(title: "Yes", style: .Default) { (_) -> Void in
    UIApplication.sharedApplication().openURL(url)
    })
  presentViewController(ac, animated: true, completion: nil)
  return false
}