Objective-C observer - how to use in Swift

Question

I'm adding new features with Swift to Objective-C app.

I have this observer in Objective-C (registration.m):

[[NSNotificationCenter defaultCenter] removeObserver:self name:NOTIFICATION_SERVER_SENT_CONFIRMATION_SMS object:nil];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(confirmSms) name:NOTIFICATION_SERVER_SENT_CONFIRMATION_SMS object:nil];

and in confirm.m:

[[NSNotificationCenter defaultCenter] postNotificationName:NOTIFICATION_SERVER_SENT_CONFIRMATION_SMS object:nil];

How to observe this in Swift? I've tried

NotificationCenter.default.removeObserver(self,
                                                  name: NOTIFICATION_SERVER_SENT_CONFIRMATION_SMS,
                                                  object:nil);

NotificationCenter.default.addObserver(self,
                                              selector:#selector(self.confirmationSmsSent),
                                              name: NOTIFICATION_SERVER_SENT_CONFIRMATION_SMS,
                                              object: nil);

And I'm getting

Use of unresolved identifier 'NOTIFICATION_SERVER_SENT_CONFIRMATION_SMS'

Thanks

// EDIT:

I have declared in Obj-C:

NSString *const NOTIFICATION_SERVER_SENT_CONFIRMATION_SMS = @"confirmationSMSSent";

Will this still work with this?

let name: NSNotification.Name = NSNotification.Name("Your_Notification_Name_Key_String") //NOTIFICATION_SERVER_SENT_CONFIRMATION_SMS

And when I use

NotificationCenter.default.addObserver(self, selector:#selector(self.confirmationSmsSent(_:)), name: name, object: nil)

func confirmationSmsSent(notification: NSNotification) {

}

I got error

Value of type 'MyController' has no member 'confirmationSmsSent'

on

NotificationCenter.default.addObserver(self, selector:#selector(self.confirmationSmsSent(_:)), name: name, object: nil)

http://stackoverflow.com/questions/36910965/how-to-pass-data-using-notificationcentre-in-swift-3-0-and-nsnotificationcenter/36911168#36911168 — Sahil, Feb 03 '17 at 09:13
in witch file you've declared NOTIFICATION_SERVER_SENT_CONFIRMATION_SMS variable? — BEN MESSAOUD Mahmoud, Feb 03 '17 at 09:19

Sohil R. Memon · Accepted Answer · 2017-02-03T11:04:33.043

3

In Swift 3, the syntax is changed. You have to define the variable of NSNotification.Name

let name: NSNotification.Name = NSNotification.Name("Your_Notification_Name_Key_String") //NOTIFICATION_SERVER_SENT_CONFIRMATION_SMS

//Add Notification
NotificationCenter.default.addObserver(self, selector:#selector(self.yourSelector(_:)), name: name, object: nil)

//Remove Notification Observer
NotificationCenter.default.removeObserver(self, name: name, object: nil)

//Your Selector
func yourSelector(_ notification: Notification) {
//Code
}

edited Feb 03 '17 at 11:04

answered Feb 03 '17 at 08:30

Sohil R. Memon

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and self.yourSelector(_:) shoud be defined as func yourSelector()? What should be in () as param? On func confirmationSmsSent(notification: NSNotification) {} I'm getting on the selector error **Value of type 'MyController' has no member 'confirmationSmsSent'** – David Feb 03 '17 at 09:46
1

@sohil-r-memon Thank you! – David Feb 03 '17 at 13:03

Anton Malmygin · Answer 2 · 2017-02-03T08:40:27.470

1

This is because you not yet declared NOTIFICATION_SERVER_SENT_CONFIRMATION_SMS.

Normally notification name is just a string, btw you must cast it to nested NSNotification.Name type.

let NOTIFICATION_SERVER_SENT_CONFIRMATION_SMS = NSNotification.Name("<some string>")

edited Feb 03 '17 at 08:40

answered Feb 03 '17 at 08:28

Anton Malmygin

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Vyacheslav · Answer 3 · 2017-02-03T09:02:50.480

1

The most useful swift - lije code is extension

extension Notification.Name {
static let someNewName = "ThatsItImAwsome" 
}

Usage inside post :

.someNewKey

this:

NotificationCenter.default.addObserver(self, selector:#selector(self.yourSelector(_:)), name: .someNewKey, object: nil)

edited Feb 03 '17 at 09:02

answered Feb 03 '17 at 08:36

Vyacheslav

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Objective-C observer - how to use in Swift

3 Answers3