如何使用 swift 3.0 中的 NotificationCenter 和 swift 2.0 中的 NSNotificationCenter 传递数据？
我正在我的 swift ios 应用程序中实现 socket.io。
目前在几个面板上，我正在监听服务器并等待传入消息。我通过调用每个面板中的 getChatMessage 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？
NSNotificationCenter.defaultCenter().postNotificationName("hideSpinner", object: nil, userInfo: yourvalue)
yourValue（在 showSpinningWheel 中）？
notification.userinfo 一样使用 .userinfo
斯威夫特 2.0
使用 userInfo 传递信息，它是 [NSObject : AnyObject] 类型的可选字典？
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、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 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)
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
}
}
}
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
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)
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)
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。
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)
}
}
