Question

我想做什么：我有一个登录屏幕，用户填写用户名和密码，然后按下登录按钮。完成对服务器的异步调用以检查用户是否已注册且密码是否正常，如果是（异步功能将bool设置为yes），则对下一个视图控制器执行segue。很简单，我尝试了很多方法，但总是遇到同样的问题，主线程运行shouldPerformSegueWithIdentifier方法，执行异步调用并在后台线程之前检查全局bool var（默认为false）已更新它，因此不执行segue，因为全局变量设置为true AFTER。只有当我使用sleep（1）时，UI才会刷新，但我不想使用它。有没有办法在没有睡觉的情况下做到这一点？我运行的每个方法都有一个完成处理程序我不知道如何将主要与后台线程同步。我已经读过它可以从异步调用更新UI，所以这应该是可行的。我已经找了一段时间的问题并尝试了很多代码片段，但仍然没有找到解决我问题的方法。这是我到目前为止的代码：

    override func shouldPerformSegueWithIdentifier(identifier: String, sender: AnyObject?) -> Bool {

    let apiCall = webApi()

    dispatch_async(dispatch_get_main_queue()) {

        apiCall.callCheckIsUserLogged(nil, password : self.passwordField.text, email: self.mailField.text){ (ok) in
        }
    }
//sleep(1) if I uncomment this, my method works because it will return true
    return userIsLogged
}

apiCall.callCheckIsUserLogged()：

typealias successClosure = (success : Bool) -> Void
    //Make a call to check if the user exist, server returns json with success or failure
func callCheckIsUserLogged(username: String?, password : String?, email: String?,completed : successClosure){

    userApiCallUrl = "http://apiurl.com/users/login"

    let call = asyncCallClass()
    call.doAsyncCallWithParams(userApiCallUrl, calltype: "POST", username: username, pass: password, mail: email){ (success) in
        completed(success: true)
    }

}

call.doAsyncCallWithParams()代码：

internal typealias completion = (success : Bool) -> Void
private var flagCompletion : Bool = false

        //Handle async class with this method
//var callType is aditioned everytime an arg is not passed nil.
//callType == 3 it is a call to check if user is logged
//callType == 2 is a call to register a new user
func doAsyncCallWithParams(url : String, calltype : String, username : String?, pass : String?, mail : String?, completed : completion){

    var callType : Int = 0


    //Set Async Url
    setUrl(url)

    //Set Post Params
    if let user : String = username{
        self.username = "username=\(user)"
        callType += 1
    }
    if let password : String = pass{
        self.password = "password=\(password)"
        callType += 1
    }
    if let mail : String = mail{
        self.email = "email=\(mail)"
        callType += 1
    }

    //register a new user
    if(callType == 3){
        paramString = "\(self.username)&\(self.password)&\(self.email)"

    }
    //check if user is logged, send email and password
    if(callType == 2){
        paramString = "\(self.email)&\(self.password)"
    }

    //Do call
    callWithCompletionHandler { (success) in
        self.flagCompletion = true
        completed(success: self.flagCompletion)
    }
}

callWithCompletionHandler()代码：

private typealias completionAsyncCall = (success : Bool) -> Void
    private func callWithCompletionHandler(completed : completionAsyncCall){
        asyncJson.removeAllObjects()

        //Set async call params
        let request = NSMutableURLRequest(URL: NSURL(string: self.url!)!)
        request.HTTPMethod = "POST"
        let trimmedPostParam : String = self.paramString!.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceCharacterSet())

        request.HTTPBody = trimmedPostParam.dataUsingEncoding(NSUTF8StringEncoding)

        let task = NSURLSession.sharedSession().dataTaskWithRequest(request) { data, response, error in
            guard error == nil && data != nil else {
                // check for fundamental networking error
                print("error=\(error)")
                return
            }
            if let httpStatus = response as? NSHTTPURLResponse where httpStatus.statusCode != 200 {
                // check for http errors
                print("statusCode should be 200, but is \(httpStatus.statusCode)")
                print("response = \(response)")
            }

            let responseString = NSString(data: data!, encoding: NSUTF8StringEncoding)


            let result : AnyObject = responseString!.parseJSONString!

                if let nsMutableResult = result as? NSMutableArray{
                    print("NSMutableArray")
                }
                if let nsDictResult = result as? NSMutableDictionary{
                    self.parseMutableDictionary(nsDictResult)
                }


            self.flag = true  // true if download succeed,false otherwise
            completed(success: flagAsyncCall!)
        }
        task.resume()
    }

Answer 1

在登录按钮上按下呼叫：

apiCall.callCheckIsUserLogged(nil, password : self.passwordField.text, email: self.mailField.text){ (ok) in
  if ok {
     self.performSegueWithIdentifier("Identifier", sender: self)
  } else {
    print("User not logged in")
   }
}

因为如果用户登录了，您的callCheckIsUserLogged方法已经返回。

internal typealias completion = (success : Bool) -> Void

异步调用后无法刷新UI

1 个答案: