Swift 3上的NotificationCenter问题 [英] NotificationCenter issue on Swift 3

问题描述

我正在学习Swift 3，我正在尝试使用 NSNotificationCenter 。这是我的代码：

I'm learning Swift 3 and I'm trying to using NSNotificationCenter. Here is my code:

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。我该如何解决这个问题？

It always gives me the error "signal SIGBRT". When I try to change the name in the observer, it's not an error, but obviously it didn't show anything. How do I fix this?

推荐答案

Swift 3& 4

Swift 3，现在是Swift 4，已经用 struct 包装器替换了许多字符串类型的API类型，与NotificationCenter的情况一样。通知现在由 struct Notfication.Name 标识，而不是由 String 标识。有关详细信息，请参阅现有的迁移到Swift 3指南

Swift 3 & 4

Swift 3, and now Swift 4, have replaced many "stringly-typed" APIs with struct "wrapper types", as is the case with NotificationCenter. Notifications are now identified by a struct Notfication.Name rather than by String. For more details see the now legacy 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被定义为静态常量 Notification.Name ;即 .UIApplicationDidFinishLaunching ， .UITextFieldTextDidChange 等。

All of the system notification types are now defined as static constants on Notification.Name; i.e. .UIApplicationDidFinishLaunching, .UITextFieldTextDidChange, etc.

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：

You can extend Notification.Name with your own custom notifications in order to stay consistent with the system notifications:

// 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 ：

Same as Swift 4, except now system notifications names are part of UIApplication. So in order to stay consistent with the system notifications you can extend UIApplication with your own custom notifications instead of Notification.Name :

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

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

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