如果在链接中返回nil，如何检查SwiftyJSON

Question

如果我的链接没有返回数据，我如何签入swiftyJSON， 我收到此错误：致命错误：在解包可选值时意外发现nil

  var URLString = mylink
        URLString = URLString.stringByAddingPercentEscapesUsingEncoding(NSUTF8StringEncoding)!

        let url = NSURL(string: URLString)!


    let task = NSURLSession.sharedSession().dataTaskWithURL(url)  {(data, response, innerError) in


         let jsonData = NSData(contentsOfURL: url)! as NSData? //>> here is the error fatal error: unexpectedly found nil while unwrapping an Optional value



        let readableJson = JSON(data: jsonData!, options: NSJSONReadingOptions.MutableContainers, error: nil)
        let jjson = readableJson[0]
        let ID = jjson["Title"]


        })





        }
    task.resume()

Answer 1

你应该避免强行解开"!"。

试试这个

func foo(urlAsString:String) {
    guard let
        urlAsStringEscaped = urlAsString.stringByAddingPercentEscapesUsingEncoding(NSUTF8StringEncoding),
        url = NSURL(string: urlAsStringEscaped)
        else { fatalError() }

    let task = NSURLSession.sharedSession().dataTaskWithURL(url)  {(data, response, error) in
        if let data = data where error == nil {
            let json = JSON(data: data)
            let id = json[0]["Title"].string
        }
    }
    task.resume()
}