我在let task = session这一行有一个错误，应用程序运行，但当json尝试加载应用程序时停止，并在控制台中显示致命错误：
展开可选值时意外找到nil
我只是尝试显示服务器上的JSON，当我更新到Xcode 7时，这个问题开始出现

class ViewController: UIViewController {

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

    let jsonUrl = "{http://test.yozzibeens.com/AppTesting/JsonArray.php}"

    let session = NSURLSession.sharedSession()
    let shotsUrl = NSURL(string: jsonUrl)

    let task = session.dataTaskWithURL(shotsUrl!)
        {
        (data, response, error) -> Void in

        do {
            let jsonData = try NSJSONSerialization.JSONObjectWithData(data!, options:NSJSONReadingOptions.MutableContainers ) as! NSDictionary

            print(String(jsonData["ip"]!))
        } catch _ {
            // Error
        }
    }

    task.resume()

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