带有 POST 请求的完成处理程序

Question

我有简单的登录方法，returns bool，取决于用户登录是否成功。我对响应顺序和代码执行有疑问。我读过有关完成处理程序的信息，我认为这是解决我的问题的方法，但我不确定。这是我的方法：

    //perform user login in, setting nsuserdefaults and returning the bool result
        func login(username: String, password:String) -> (Bool) {

            var success:Bool = false

            //sending inputs to server and receiving info from server
            let postRequest = postDataToURL()
            postRequest.link = "http://pnc.hr/rfid/login.php"
            postRequest.postVariables = "username=" + username + "&password=" + pass

word

        postRequest.forData("POST") { jsonString in
            // getting the result from the asinhronys task
            let result = convertStringToDictionary(jsonString as String)
            if let loggedIn = result?["loggedIn"] as? Bool where loggedIn == true {

                let userType = result?["userType"] as? String
                let token = result?["token"] as? String

                //if user is logged - setting parameters in Key Chains and redirecting them to the menu view
                let defaults = NSUserDefaults.standardUserDefaults()
                defaults.setObject(loggedIn, forKey: "loggedIn")
                defaults.setObject(username, forKey: "username")
                defaults.setObject(userType, forKey: "userType")
                defaults.setObject(token, forKey: "token")

                success = true
            }
            else {
                success = false
            }
            print ("class - " + String(jsonString))
            print ("classIN - " + String(success))
        }

        print ("classOUT - " + String(success))
        return success
    }

我想在检查变量 loggedIn 的 if 语句中使成功变量 return 等于 true。但在那种情况下我会出错。

那我就做了这个方法。问题是 return 方法比 POST 请求更快地完成变量成功。所以它在任何情况下都是错误的。我打印了变量以查看代码执行的顺序，方法首先打印 "classOUT"、returns 变量，然后设置变量值并打印 "classIN"。

我怎样才能等到记录用户的代码被执行，这样我才能获得变量 success 的正确值？

Answer 1

执行用户登录，设置nsuserdefaults并返回bool结果

completionBlock: 是当您像任何块一样调用它时将执行的块，但您可以选择何时以及通过该块的所有内容。

    func login(username: String, password:String,completionBlock : ((success : Bool)->Void)){

        //sending inputs to server and receiving info from server
        let postRequest = postDataToURL()
        postRequest.link = "http://pnc.hr/rfid/login.php"
        postRequest.postVariables = "username=" + username + "&password=" + password

    postRequest.forData("POST") { jsonString in
        // getting the result from the asinhronys task
        let result = convertStringToDictionary(jsonString as String)
        if let loggedIn = result?["loggedIn"] as? Bool where loggedIn == true {

            let userType = result?["userType"] as? String
            let token = result?["token"] as? String

            //if user is logged - setting parameters in Key Chains and redirecting them to the menu view
            let defaults = NSUserDefaults.standardUserDefaults()
            defaults.setObject(loggedIn, forKey: "loggedIn")
            defaults.setObject(username, forKey: "username")
            defaults.setObject(userType, forKey: "userType")
            defaults.setObject(token, forKey: "token")

            completionBlock(success:true)
        }
        else {
            completionBlock(success:false)
        }
    }
}

当你调用它时，它看起来像这样：-

    login(username: String, password:String,completionBlock : { (success) in
     print(success)
  })

Answer 2

你可以这样做

func login(username: String, password: String, completion: (Bool) -> ()) {


    ... YOUR USUAL NETWORKING CODE ...


    completion(success)

}

然后调用它

login(username: anonymous, password: ******) { authStatus in

    if authStatus == true {
        print("user in")
    } else {
        print("try one more time")
    }

}

带有 POST 请求的完成处理程序

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completionhandler

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