条件绑定的初始化程序必须具有可选类型，而不是“ UInt”

Question

func loadRequest() {
    var url : URL
    if (self.url?.hasPrefix(localPrefix) == true) {
        let appDelegate = UIApplication.shared.delegate as! AppDelegate
        if let port = appDelegate.webserver.port {
            let startIndex = self.url?.characters.index((self.url?.startIndex)!, offsetBy: localPrefix.characters.count)
            let endIndex = self.url?.range(of: "/", options: NSString.CompareOptions.literal, range: startIndex! ..< (self.url?.endIndex)!)
            let strURL = localPrefix + String(describing: port) + (self.url?.substring(from: (endIndex?.lowerBound)!))!
            url = URL(string: strURL)!
        } else {
            return
        }
    } else if (self.url?.hasPrefix("http") == true) {
        url = URL(string: self.url!)!
    } else {
        url = URL(string: self.url!)!
    }

    print("Loading URL: \(url.absoluteString)")
    let request = URLRequest(url: url, cachePolicy: NSURLRequest.CachePolicy.useProtocolCachePolicy, timeoutInterval: 10)

    webView!.load(request)
}

上面部分的错误行

if let port = appDelegate.webserver.port {

错误>>用于条件绑定的初始化程序必须具有可选类型，而不是“ UInt”

如何解决呢？