IOS Swift - 从 NURLSESSION 获取统计数据后转到另一个 View

Question

一旦用户单击登录按钮，我将调用函数LoginClicked并从api获取状态:

func LoginClicked(sender: AnyObject)
{
    data_request{
        (response) -> () in
            let arrResponse = response.componentsSeparatedByString("|")
            if (arrResponse[2] == "1"){
                self.performSegueWithIdentifier("Login", sender: self)
            }
            else {
                let alert = UIAlertController(title: "Login Failed", message: "Invalid Login!", preferredStyle: UIAlertControllerStyle.Alert)           
                alert.addAction(UIAlertAction(title: "Click", style: UIAlertActionStyle.Default, handler: nil))         
                self.presentViewController(alert, animated: true, completion: nil)
            }
    }
}


func data_request(completion : (response:NSString) -> ()){
    let txtUI : String = txtUsername!.text!
    let txtPWD : String = txtPassword!.text!
    let url = NSURL(string: "http://myweb.net/?UI=\(txtUI)&PW=\(txtPWD)")!
    let request = NSURLRequest(URL: url)
    let config = NSURLSessionConfiguration.defaultSessionConfiguration()
    let session = NSURLSession(configuration: config)

    let task = session.dataTaskWithRequest(request, completionHandler: {
        (
        let data, let response, let error) in

        guard let _:NSData = data, let _:NSURLResponse = response  where error == nil else {
            print("error")
            return
        }

        let dataString = NSString(data: data!, encoding: NSUTF8StringEncoding)
        completion(response : dataString!)

    })
    task.resume()
}

如果成功，它将移动到另一个 View 。否则，显示失败警报。在这两种情况下调用 self. 时，它都会遇到错误 BAD_EXECUTION_INSTRUCTION。

Answer 1

得到@Tj3n的提示后，现在可以执行正确的操作了。

func data_request(completion : (response:NSString) -> ()){
    let txtUI : String = txtUsername!.text!
    let txtPWD : String = txtPassword!.text!
    let url = NSURL(string: "http://myweb.net/?UI=\(txtUI)&PW=\(txtPWD)")!
    let request = NSURLRequest(URL: url)
    let config = NSURLSessionConfiguration.defaultSessionConfiguration()
    let session = NSURLSession(configuration: config)

    let task = session.dataTaskWithRequest(request, completionHandler: {
        (
        let data, let response, let error) in

        guard let _:NSData = data, let _:NSURLResponse = response  where error == nil else {
            print("error")
            return
        }
    dispatch_async(dispatch_get_main_queue(), {
                let dataString = NSString(data: data!, encoding: NSUTF8StringEncoding)
                //let response = dataString?.componentsSeparatedByString("|")
                //print(dataString)
                //print(response![2])
                let arrResponse = dataString!.componentsSeparatedByString("|")
                if (arrResponse[2] == "1"){
                    self.performSegueWithIdentifier("Login", sender: self)
                }
                else {
                    let alert = UIAlertController(title: "Login Failed", message: "Invalid Login!", preferredStyle: UIAlertControllerStyle.Alert)

                    alert.addAction(UIAlertAction(title: "Click", style: UIAlertActionStyle.Default, handler: nil))

                    self.presentViewController(alert, animated: true, completion: nil)
                }
            })
let dataString = NSString(data: data!, encoding: NSUTF8StringEncoding)
        completion(response : dataString!)

    })
    task.resume()
}