149

我正在socket.io我的 swift ios 应用程序中实施。

目前在几个面板上，我正在监听服务器并等待传入​​消息。我通过调用getChatMessage每个面板中的函数来做到这一点：

func getChatMessage(){
    SocketIOManager.sharedInstance.getChatMessage { (messageInfo) -> Void in
        dispatch_async(dispatch_get_main_queue(), { () -> Void in
            //do sth depending on which panel user is
        })
    }
}

但是我注意到这是一种错误的方法，我需要更改它 - 现在我只想开始收听传入的消息一次，并且当任何消息到来时 - 将此消息传递给任何收听它的面板。

所以我想通过 NSNotificationCenter 传递传入的消息。到目前为止，我能够传递发生某事的信息，但不能传递数据本身。我是这样做的：

NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(ViewController.showSpinningWheel(_:)), name: showSpinner, object: nil)

然后我有一个函数叫做：

func showSpinningWheel(notification: NSNotification) {
}

任何时候我想称之为我都在做：

NSNotificationCenter.defaultCenter().postNotificationName(hideSpinner, object: self)

那么如何传递对象messageInfo并将其包含在被调用的函数中呢？

4

7 回答 7

330

斯威夫特 2.0

userInfo使用[NSObject : AnyObject] 类型的可选字典传递信息？

  let imageDataDict:[String: UIImage] = ["image": image]

  // Post a notification
  NSNotificationCenter.defaultCenter().postNotificationName(notificationName, object: nil, userInfo: imageDataDict)

 // Register to receive notification in your class
 NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(self.showSpinningWheel(_:)), name: notificationName, object: nil)

 // handle notification
 func showSpinningWheel(notification: NSNotification) { 

  if let image = notification.userInfo?["image"] as? UIImage {
  // do something with your image   
  }
 }

Swift 3.0、4.0、5.0 及以上版本

userInfo 现在采用 [AnyHashable: Any]？作为参数，我们在 Swift 中作为字典文字提供

  let imageDataDict:[String: UIImage] = ["image": image]

  // post a notification
  NotificationCenter.default.post(name: NSNotification.Name(rawValue: "notificationName"), object: nil, userInfo: imageDataDict) 
  // `default` is now a property, not a method call

 // Register to receive notification in your class
 NotificationCenter.default.addObserver(self, selector: #selector(self.showSpinningWheel(_:)), name: NSNotification.Name(rawValue: "notificationName"), object: nil)

 // handle notification
 // For swift 4.0 and above put @objc attribute in front of function Definition  
 func showSpinningWheel(_ notification: NSNotification) {

  if let image = notification.userInfo?["image"] as? UIImage {
  // do something with your image   
  }
 }

注意：通知“名称”不再是字符串，而是 Notification.Name 类型，因此我们使用它的原因NSNotification.Name(rawValue: "notificationName")，我们可以使用我们自己的自定义通知扩展 Notification.Name。

extension Notification.Name {
static let myNotification = Notification.Name("myNotification")
}

// and post notification like this
NotificationCenter.default.post(name: .myNotification, object: nil)
于 2016-04-28T09:55:41.633 回答
61

对于斯威夫特 3

let imageDataDict:[String: UIImage] = ["image": image]

  // post a notification
  NotificationCenter.default.post(name: NSNotification.Name(rawValue: "notificationName"), object: nil, userInfo: imageDataDict) 
  // `default` is now a property, not a method call

 // Register to receive notification in your class
 NotificationCenter.default.addObserver(self, selector: #selector(self.showSpinningWheel(_:)), name: NSNotification.Name(rawValue: "notificationName"), object: nil)

 // handle notification
 func showSpinningWheel(_ notification: NSNotification) {
        print(notification.userInfo ?? "")
        if let dict = notification.userInfo as NSDictionary? {
            if let id = dict["image"] as? UIImage{
                // do something with your image
            }
        }
 }

对于斯威夫特 4

let imageDataDict:[String: UIImage] = ["image": image]

  // post a notification
  NotificationCenter.default.post(name: NSNotification.Name(rawValue: "notificationName"), object: nil, userInfo: imageDataDict) 
  // `default` is now a property, not a method call

 // Register to receive notification in your class
 NotificationCenter.default.addObserver(self, selector: #selector(self.showSpinningWheel(_:)), name: NSNotification.Name(rawValue: "notificationName"), object: nil)

 // handle notification
 @objc func showSpinningWheel(_ notification: NSNotification) {
        print(notification.userInfo ?? "")
        if let dict = notification.userInfo as NSDictionary? {
            if let id = dict["image"] as? UIImage{
                // do something with your image
            }
        }
 }
于 2018-07-31T11:13:20.183 回答
21

你好@sahil 我更新了你对 swift 3 的回答

let imageDataDict:[String: UIImage] = ["image": image]

  // post a notification
  NotificationCenter.default.post(name: NSNotification.Name(rawValue: "notificationName"), object: nil, userInfo: imageDataDict) 
  // `default` is now a property, not a method call

 // Register to receive notification in your class
 NotificationCenter.default.addObserver(self, selector: #selector(self.showSpinningWheel(_:)), name: NSNotification.Name(rawValue: "notificationName"), object: nil)

 // handle notification
 func showSpinningWheel(_ notification: NSNotification) {
        print(notification.userInfo ?? "")
        if let dict = notification.userInfo as NSDictionary? {
            if let id = dict["image"] as? UIImage{
                // do something with your image
            }
        }
 }

希望它有帮助。谢谢

于 2017-06-07T07:22:36.173 回答
9

这就是在 Swift 5 中对我有用的

NotificationCenter.default.addObserver(self,
                                       selector: #selector(handleMassage),
                                       name: Notification.Name("NotificationName"),
                                       object: nil)

处理通知的方法：

    @objc func handleMassage(notification: NSNotification) {
    if let dict = notification.object as? NSDictionary {
        if let myMessage = dict["myMessage"] as? String{
            myLabel.text = myMessage
        }
    }
}

我是这样发布的：

let dic = ["myMessage": "testing"]
NotificationCenter.default.post(name: Notification.Name("NotificationName"), object: dic)
于 2021-03-21T05:49:49.707 回答
3

这就是我实现它的方式。 

let dictionary = self.convertStringToDictionary(responceString)            
     NotificationCenter.default.post(name: NSNotification.Name(rawValue: "SOCKET_UPDATE"), object: dictionary)
于 2018-08-24T22:07:30.493 回答
0

Swift 5.5与避免#selector()：

首先，声明名称：

extension Notification.Name {
    static let prettyName = Notification.Name("MyPrettyName")
}

接下来是添加观察者（注意队列）：

// For example transferred data should implement protocol
protocol PrettyDelegate {
    func doSomethingAwesome()
}

// Here is the way how we can subscribe as observer
NotificationCenter.default.addObserver(forName: .prettyName, object: nil, queue: nil) { [weak self] notif in
    guard let self = self else { return } // Because self used more than once
    if let userInfo = notif.userInfo,
       let delegate = userInfo["pretty"] as? PrettyDelegate {
        self.delegate = delegate
    }
    
    self.makePretty() // Here we can do anything
}

最后，我们可以从另一个对象发布通知

// Here I'll illustrate how to pass optional value as userInfo
var userInfo: [AnyHashable : Any]?
if let prettyDelegate = self as? PrettyDelegate {
    userInfo = ["pretty": prettyDelegate]
}
NotificationCenter.default.post(name: .prettyName, object: nil, userInfo: userInfo)

注意：当您不再需要它时，不要忘记移除观察者。

于 2022-02-09T13:39:56.997 回答
0

在 swift 4.2 中，我使用以下代码显示和隐藏使用 NSNotification 的代码

 @objc func keyboardWillShow(notification: NSNotification) {
    if let keyboardSize = (notification.userInfo? [UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
        let keyboardheight = keyboardSize.height
        print(keyboardheight)
    }
}
于 2019-05-07T09:27:42.480 回答