为什么func调用中的代码块没有被执行？答案

【问题标题】：why is the block of code inside func call is not executed?为什么func调用中的代码块没有被执行？
【发布时间】：2016-07-10 06:07:56
【问题描述】：

我正在尝试在我的应用程序中实现一个 Xmpp 客户端。我计划在我的应用程序中使用以下代码，但部分代码似乎没有执行，这会阻止我连接到服务器。 https://github.com/processone/xmpp-messenger-ios

我正在尝试使用我的 jabberID 和密码连接到服务器，但对于某些人来说，此代码永远不会执行：

if let _ = error {
     let alertController = UIAlertController(title: "Sorry", message: "An error occured: \(error)", preferredStyle: UIAlertControllerStyle.Alert)
         alertController.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.Default, handler: { (UIAlertAction) -> Void in
         //do smt
     }))
        self.presentViewController(alertController, animated: true, completion: nil)
     } else {
        self.dismissViewControllerAnimated(true, completion: nil)
     }

这是与问题相关的整个代码：

    @IBAction func validate(sender: AnyObject) {
            if OneChat.sharedInstance.isConnected() {
                OneChat.sharedInstance.disconnect()
                usernameTextField.hidden = false
                passwordTextField.hidden = false
                validateButton.setTitle("Validate", forState: UIControlState.Normal)
            } else {
                OneChat.sharedInstance.connect(username: self.usernameTextField.text!, password: self.passwordTextField.text!) {(stream, error) -> Void in
                    if let _ = error {
                        let alertController = UIAlertController(title: "Sorry", message: "An error occured: \(error)", preferredStyle: UIAlertControllerStyle.Alert)
                        alertController.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.Default, handler: { (UIAlertAction) -> Void in
                            //do smt
                        }))
                        self.presentViewController(alertController, animated: true, completion: nil)
                    } else {
                        self.dismissViewControllerAnimated(true, completion: nil)
                    }
                }
            }
        }

public typealias OneChatConnectCompletionHandler = (stream: XMPPStream, error: DDXMLElement?) -> Void

public func connect(username username: String, password: String, completionHandler completion:OneChatConnectCompletionHandler) {
        if isConnected() {
            streamDidConnectCompletionBlock = completion
            self.streamDidConnectCompletionBlock!(stream: self.xmppStream!, error: nil)
            return
        }

        if (username == "kXMPPmyJID" && NSUserDefaults.standardUserDefaults().stringForKey(kXMPP.myJID) == "kXMPPmyJID") || (username == "kXMPPmyJID" && NSUserDefaults.standardUserDefaults().stringForKey(kXMPP.myJID) == nil) {
            streamDidConnectCompletionBlock = completion
            streamDidConnectCompletionBlock!(stream: self.xmppStream!, error: DDXMLElement(name: "Please set crendentials before trying to connect"))
            return
        }

        if username != "kXMPPmyJID" {
            setValue(username, forKey: kXMPP.myJID)
            setValue(password, forKey: kXMPP.myPassword)
        }

        if let jid = NSUserDefaults.standardUserDefaults().stringForKey(kXMPP.myJID) {
            xmppStream?.myJID = XMPPJID.jidWithString(jid)
        } else {
            streamDidConnectCompletionBlock = completion //was false
            streamDidConnectCompletionBlock!(stream: self.xmppStream!, error: DDXMLElement(name: "Bad username"))
        }

        if let password = NSUserDefaults.standardUserDefaults().stringForKey(kXMPP.myPassword) {
            self.password = password
        } else {
            streamDidConnectCompletionBlock = completion //was false
            streamDidConnectCompletionBlock!(stream: self.xmppStream!, error: DDXMLElement(name: "Bad password"))
        }
        try! xmppStream!.connectWithTimeout(XMPPStreamTimeoutNone)

        streamDidConnectCompletionBlock = completion
    }

【问题讨论】：

您的代码的哪一部分没有被执行。
正如我在上面指出的以 if let _ = error 开头的代码
你得到的错误值是多少？或者你的响应块没有被调用？
我没有收到任何错误，但据我从代码中了解，
如果错误值为 nil 那么它应该执行 else 部分。尝试明确检查错误！=nil

标签： ios swift xmpp

【解决方案1】：

也许，您期望永远不会发生超时（库的配置）我有同样的问题，最后，我发现我的问题是主机名和端口。您是否尝试过使用这样的东西：

let usuario = "name@domain.com";

OneChat.sharedInstance.connect(username: usuario, password: pass) { (stream, error) -> Void in


        if let _ = error {
            let alertController = UIAlertController(title: "Sorry", message: "An error occured: \(error)", preferredStyle: UIAlertControllerStyle.Alert)
            alertController.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.Default, handler: { (UIAlertAction) -> Void in
                //do something
            }))
            self.presentViewController(alertController, animated: true, completion: nil)
        } else {
            print("I did it!")

        }
    }

【讨论】：