WebView中的空白页

Question

加载网页时出现黑屏:(

if let url = self.postLink {
    print("Go to: \(url)")
    var newUrl = URL(string: url)
    var urlRequest = URLRequest(url: newUrl!)
    webView?.delegate = self
    webView?.scalesPageToFit = true
    webView?.loadRequest(urlRequest)
}

“转到：”显示正确的网址。我做错了什么？