NotificationCenter issue on Swift 3

Question

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      and this is the observer    override func viewDidLoad         super viewDidLoad     codeerorr     NotificationCenter default   addObserver self  selector  Selector   onPostLoaded     name   loadedPost   object  nil     func numberOfSections in tableView  UITableView  - gt  Int       return 1     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

User · Answer

I think it has changed again   For posting this works in Xcode 8 2   NotificationCenter default post Notification name  UIApplicationWillResignActive

User · Answer

Swift 3  amp  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 usage      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  amp  4 usage      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    All of the system notification types are now defined as static constants on Notification Name  i e   UIApplicationDidFinishLaunching   UITextFieldTextDidChange  etc   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 usage   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

User · Answer

For all struggling around with the  selector in Swift 3 or Swift 4  here a full code example      WE NEED A CLASS THAT SHOULD RECEIVE NOTIFICATIONS     class MyReceivingClass           ---------------------------------------------        INIT - gt  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 - gt  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              In this example we try to get POSTs from AppDelegate  so in AppDelegate implement this       ---------------------------------------------    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

User · Answer

Notifications appear to have changed again  October 2016       Register to receive notification  NotificationCenter default addObserver self  selector   selector yourClass yourMethod   name  NSNotification Name rawValue   yourNotificatioName    object  nil       Post notification  NotificationCenter default post name  NSNotification Name rawValue   yourNotificationName    object  nil

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