小编典典

如何在Swift 3.0中使用NotificationCenter和在Swift 2.0中使用NSNotificationCenter传递数据?

swift

我正在socket.io快速的ios应用程序中实现。

目前,在几个面板上,我正在侦听服务器并等待传入​​消息。我这样做是通过getChatMessage在每个面板中调用该函数:

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个错误的方法,我需要更改它-现在我只想开始监听一次传入的消息,并且当出现任何消​​息时-将此消息传递给任何侦听它的面板。

所以我想通过NSNotificationCenter传递传入的消息。到目前为止,我能够传递发生了某些事情的信息,但无法传递数据本身。我这样做的原因是:

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) {
}

每当我想称呼它时,我都在做:

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

那么如何传递对象messageInfo并将其包含在调用的函数中呢?


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2020-07-07

共1个答案

小编典典

雨燕2.0

传递信息使用的userInfo是[NSObject:AnyObject]类型的可选词典?

  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及更高版本

现在,userInfo需要[AnyHashable:Any]吗?作为参数,我们在Swift中将其作为字典文字提供

  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,而是类型为Notification.Name,因此,为什么要使用它NSNotification.Name(rawValue:"notificationName"),我们可以使用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)
2020-07-07