NotificationCenter is not calling the selector - ios

Question

I've searched about this but the problem still exist for me. I found this great question but unfortunately it didn't work for me. This is the first time I'm working with NotificationCenter and the need to use this first occurs when I wanted to pass data to a viewcontroller under a tab of XLPagerTabStrip.
So here is how I am posting the Notification:
if let doc_ID = mainDoctorsArray[sender.tag].doctors_id {
NotificationCenter.default.post(name: Notification.Name("docID"), object: nil, userInfo: ["value" : doc_ID])
}
In the class I've made for observing this notification I'm calling NotificationCenter.default.addObserver(self, selector: #selector(gotDocID), name: Notification.Name("docID"), object: nil)
The selector method is:
func gotDocID(notification:NSNotification) {
let userInfo:Dictionary<String,String> = notification.userInfo as! Dictionary<String,String>
if let item = userInfo["value"] {
getDoctorDetails(docID: Int(item)!)
//print(item,self)
}
}
I've also tried adding observer as:
NotificationCenter.default.addObserver(self, selector: #selector(AvailableViewController.gotDocID(notification:)), name: Notification.Name("docID"), object: nil) but still same result.
The issue is that func gotDocID(notification:NSNotification) is not being called.
UPDATE
Class which is posting the notification is ViewController.swift and the class which has the observer is AvailableViewController.swift
Based on a comment I've changed observer to NotificationCenter.default.addObserver(self, selector: #selector(AvailableViewController.gotDocID(notific‌​ation:)), name: Notification.Name("NotificationIdentifier"), object: nil) and this error is generated.
and also by doing the follow I'm getting the same error.
Value of type 'AvailableViewController' has no member 'gotDocID'

Answer 1

You can use the below code to post and get data.
//Post notification
NSNotificationCenter.defaultCenter().postNotificationName("docID", object: nil, userInfo: ["value" : doc_ID])
//Get data from observer
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(AvailableViewController.gotDocID(_:)), name: "docID", object: nil)
//Method called after notification is posted.
func gotDocID(notification: NSNotification) {
if let image = notification.userInfo?["value"] as? String {
// do something with your data
}
}

Answer 2

Please check :
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
NotificationCenter.default.addObserver(self, selector: #selector(self.gotDocID(notification:)), name: Notification.Name("docID"), object: nil)
}
#IBAction func saveButton(_ sender: UIButton) {
NotificationCenter.default.post(name: Notification.Name("docID"), object: nil, userInfo: ["value" : "123"])
}
#objc func gotDocID(notification:NSNotification) {
let userInfo:[String: String] = notification.userInfo as! [String: String]
if let item = userInfo["value"] {
print(item,self)
}
}
}

Answer 3

Add #objc to your function
#objc func gotDocID(notification:NSNotification) {
}
// Define identifier
let notificationName = Notification.Name("docID")
// Register to receive notification
NotificationCenter.default.addObserver(self, selector: #selector(AvailableViewController.gotDocID(notification:)), name: notificationName, object: nil)
// Post notification
NotificationCenter.default.post(name: notificationName, object: nil)
// Stop listening notification
NotificationCenter.default.removeObserver(self, name: notificationName, object: nil);

Answer 4

Why dont you try closure
Make sure your post notification occures.
Change
NotificationCenter.default.post(name: Notification.Name("docID") , object: ["value" : doc_ID])
NotificationCenter.default.addObserver(forName: Notification.Name("docID"), object: nil, queue: OperationQueue.main) { (notify) in
print(notify.object as! Dictionary<String,String>)
}