这个问题在这里已有答案：

NSNotificationCenter addObserver in Swift 11个答案

我试图使用 NSNotificationCenter . 这是我的代码：

func savePost(){
    let postData = NSKeyedArchiver.archivedData(withRootObject: _loadedpost)
    UserDefaults.standard().object(forKey: KEY_POST)
}
func loadPost(){
    if let postData = UserDefaults.standard().object(forKey: KEY_POST) as? NSData{
        if let postArray = NSKeyedUnarchiver.unarchiveObject(with: postData as Data) as? [Post]{
                _loadedpost = postArray
        }
    }
    //codeerror
    NotificationCenter.default().post(NSNotification(name: "loadedPost" as NSNotification.Name, object: nil) as Notification)
}

这是观察者：

override func viewDidLoad() {
    super.viewDidLoad()
//codeerorr
    NotificationCenter.default().addObserver(self, selector: Selector(("onPostLoaded")), name: "loadedPost", object: nil)
}

func numberOfSections(in tableView: UITableView) -> Int {
    return 1
}

它总是给我错误“信号SIGBRT” . 当我尝试在观察者中更改名称时，这不是错误，但显然它没有显示任何内容 . 我该如何解决？

4 回答

斯威夫特3＆4

Swift 3，现在是Swift 4，已经用 struct "wrapper types"替换了许多"stringly-typed" API，就像NotificationCenter一样 . 通知现在由 struct Notfication.Name 而不是 String 标识 . 有关详细信息，请参阅现在的遗产Migrating to Swift 3 guide

Swift 2.2 用法：

// Define identifier
let notificationIdentifier: String = "NotificationIdentifier"

// Register to receive notification
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(YourClassName.methodOfReceivedNotification(_:)), name: notificationIdentifier, object: nil)

// Post a notification
NSNotificationCenter.defaultCenter().postNotificationName(notificationIdentifier, object: nil)

Swift 3 & 4 用法：

// Define identifier
let notificationName = Notification.Name("NotificationIdentifier")

// Register to receive notification
NotificationCenter.default.addObserver(self, selector: #selector(YourClassName.methodOfReceivedNotification), name: notificationName, object: nil)

// Post notification
NotificationCenter.default.post(name: notificationName, object: nil)

// Stop listening notification
NotificationCenter.default.removeObserver(self, name: notificationName, object: nil)

现在，所有系统通知类型都定义为 Notification.Name 上的静态常量;即 .UIApplicationDidFinishLaunching ， .UITextFieldTextDidChange 等

您可以使用自己的自定义通知扩展 Notification.Name ，以便与系统通知保持一致：

// Definition:
extension Notification.Name {
    static let yourCustomNotificationName = Notification.Name("yourCustomNotificationName")
}

// Usage:
NotificationCenter.default.post(name: .yourCustomNotificationName, object: nil)

Swift 4.2 用法：

与Swift 4相同，但现在系统通知名称是UIApplication的一部分 . 因此，为了与系统通知保持一致，您可以使用自己的自定义通知而不是Notification.Name扩展 UIApplication ：

// Definition:
UIApplication {
    public static let yourCustomNotificationName = Notification.Name("yourCustomNotificationName")
}

// Usage:
NotificationCenter.default.post(name: UIApplication.yourCustomNotificationName, object: nil)

回复于 2024-05-03T09:31:21+08:00

对于所有在Swift 3或Swift 4中使用#selector的人来说，这是一个完整的代码示例：

// WE NEED A CLASS THAT SHOULD RECEIVE NOTIFICATIONS
    class MyReceivingClass {

    // ---------------------------------------------
    // INIT -> GOOD PLACE FOR REGISTERING
    // ---------------------------------------------
    init() {
        // WE REGISTER FOR SYSTEM NOTIFICATION (APP WILL RESIGN ACTIVE)

        // Register without parameter
        NotificationCenter.default.addObserver(self, selector: #selector(MyReceivingClass.handleNotification), name: .UIApplicationWillResignActive, object: nil)

        // Register WITH parameter
        NotificationCenter.default.addObserver(self, selector: #selector(MyReceivingClass.handle(withNotification:)), name: .UIApplicationWillResignActive, object: nil)
    }

    // ---------------------------------------------
    // DE-INIT -> LAST OPTION FOR RE-REGISTERING
    // ---------------------------------------------
    deinit {
        NotificationCenter.default.removeObserver(self)
    }

    // either "MyReceivingClass" must be a subclass of NSObject OR selector-methods MUST BE signed with '@objc'

    // ---------------------------------------------
    // HANDLE NOTIFICATION WITHOUT PARAMETER
    // ---------------------------------------------
    @objc func handleNotification() {
        print("RECEIVED ANY NOTIFICATION")
    }

    // ---------------------------------------------
    // HANDLE NOTIFICATION WITH PARAMETER
    // ---------------------------------------------
    @objc func handle(withNotification notification : NSNotification) {
        print("RECEIVED SPECIFIC NOTIFICATION: \(notification)")
    }
}

在这个例子中，我们尝试从AppDelegate获取POST（所以在AppDelegate中实现这个）：

// ---------------------------------------------
// WHEN APP IS GOING TO BE INACTIVE
// ---------------------------------------------
func applicationWillResignActive(_ application: UIApplication) {

    print("POSTING")

    // Define identifiyer
    let notificationName = Notification.Name.UIApplicationWillResignActive

    // Post notification
    NotificationCenter.default.post(name: notificationName, object: nil)
}

回复于 2024-05-03T09:31:21+08:00

322

通知似乎再次发生变化（2016年10月） .

//注册接收通知

NotificationCenter.default.addObserver(self, selector: #selector(yourClass.yourMethod), name: NSNotification.Name(rawValue: "yourNotificatioName"), object: nil)

//发布通知

NotificationCenter.default.post(name: NSNotification.Name(rawValue: "yourNotificationName"), object: nil)

回复于 2024-05-03T09:31:21+08:00

15
我认为它已经改变了 .

对于发布，这适用于Xcode 8.2 .
```
NotificationCenter.default.post(Notification(name:.UIApplicationWillResignActive)
```
回复于 2024-05-03T09:31:21+08:00

Swift 3上的NotificationCenter问题[重复]

4 回答

斯威夫特3＆4

相关问题