How to pass data using NotificationCenter in swift 3 0 and NSNotificationCenter in swift 2 0

Question

I m implementing socket io in my swift ios app    Currently on several panels I m listening to the server and wait for incoming messages  I m doing so by calling the getChatMessage function in each panel   func getChatMessage        SocketIOManager sharedInstance getChatMessage    messageInfo  - gt  Void in         dispatch async dispatch get main queue         - gt  Void in               do sth depending on which panel user is                      However I noticed it s a wrong approach and I need to change it - now I want to start listening for incoming messages only once and when any message comes - pass this message to any panel that listens to it   So I want to pass the incoming message through the NSNotificationCenter  So far I was able to pass the information that something happened  but not pass the data itself  I was doing that by   NSNotificationCenter defaultCenter   addObserver self  selector   selector ViewController showSpinningWheel       name  showSpinner  object  nil    then I had a function called    func showSpinningWheel notification  NSNotification        and any time I wanted to call it I was doing   NSNotificationCenter defaultCenter   postNotificationName hideSpinner  object  self    So how can I pass the object messageInfo and include it in the function that gets called

User · Answer

In swift 4 2 I used following code to show and hide code using NSNotification    objc func keyboardWillShow notification  NSNotification        if let keyboardSize    notification userInfo   UIResponder keyboardFrameEndUserInfoKey  as  NSValue   cgRectValue           let keyboardheight   keyboardSize height         print keyboardheight

User · Answer

For Swift 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                              For Swift 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

User · Answer

Hello  sahil I update your answer for swift 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                              Hope it s helpful  Thanks

User · Answer

this is how I implement it         let dictionary   self convertStringToDictionary responceString                   NotificationCenter default post name  NSNotification Name rawValue   SOCKET UPDATE    object  dictionary

User · Answer

Swift 2 0 Pass info using userInfo which is a optional Dictionary of type  NSObject   AnyObject     let imageDataDict  String  UIImage      quot image quot   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   quot image quot   as  UIImage        do something with your image            Swift 3 0 version and above The userInfo now takes  AnyHashable Any   as an argument  which we provide as a dictionary literal in Swift   let imageDataDict  String  UIImage      quot image quot   image        post a notification   NotificationCenter default post name  NSNotification Name rawValue   quot notificationName quot    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   quot notificationName quot    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   quot image quot   as  UIImage        do something with your image            NOTE  Notification    names    are no longer strings  but are of type Notification Name  hence why we are using NSNotification Name rawValue  quot notificationName quot   and we can extend Notification Name with our own custom notifications  extension Notification Name   static let myNotification   Notification Name  quot myNotification quot         and post notification like this NotificationCenter default post name   myNotification  object  nil

[ios] How to pass data using NotificationCenter in swift 3.0 and NSNotificationCenter in swift 2.0?

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