在httpPost之后，PushViewController不起作用

Question

我制作了一個登錄屏幕，該屏幕接受輸入並與REST API通信以驗證用戶。 如果響應為真，則我不登錄用戶。 我寫了一個方法openViewControllerBasedOnIdentifier（id）來切換視圖。

REST API會正確返回true和false。 推送控制器被調用，但視圖不變。 如果我僅在LoginAction方法'self.openViewControllerBasedOnIdentifier（“ PlayVC”）'中放置一行，並刪除其余代碼，該方法將正常工作。

這是我的代碼@IBAction func LoginAction（_ sender：Any）{

    //self.openViewControllerBasedOnIdentifier("PlayVC")

Constants.login_status = false
    //created NSURL
    let requestURL = NSURL(string: URL_BK)

    //creating NSMutableURLRequest
    let request = NSMutableURLRequest(url: requestURL! as URL)

    //setting the method to post
    request.httpMethod = "POST"
    let username = phonenumber.text

    //creating the post parameter by concatenating the keys and values from text field
    let postParameters = "username="+username!+"&password=bk&schoolId=0";

    //adding the parameters to request body
    request.httpBody = postParameters.data(using: String.Encoding.utf8)


    //creating a task to send the post request
    let task = URLSession.shared.dataTask(with: request as URLRequest){
        data, response, error in
        let responseData = String(data: data!, encoding: String.Encoding.utf8)
        if error != nil{
            print("error is \(error)")
            return;
        }

        //parsing the response
        do {

            print(“Received data is ---%@",responseData as Any)

            let myJSON =  try JSONSerialization.jsonObject(with: data! , options: .allowFragments) as? NSDictionary


            if let parseJSON = myJSON {


                var status : Bool!

                status = parseJSON["status"] as! Bool?
                //print(status)

                if status==false
                {
                    Constants.login_status = false

                                        }
                else{
                    Constants.login_status = true
                    print("calling PLAYVC")

                    self.openViewControllerBasedOnIdentifier("PlayVC")


                }

            }
            else{
                print("NULL VALUE RECEIVED")
            }


        } catch {
            print(error)
        }

    }
    //executing the task
    task.resume()




}

Answer 1

您應該像這樣在主線程上打開新的視圖控制器：

DispatchQueue.main.async {
    self.openViewControllerBasedOnIdentifier("PlayVC")
}

當您調用URLSession.shared.dataTask時，您的REST API查詢響應將在后台線程中處理，因此，當您調用任何UI動作時，都應按上述方式包裝代碼以在主線程中執行UI代碼。 然后就可以了:)