didUpdatePushCredentials not get called

If you're running a newer xcode (I'm on xcode 9) then VOIP is not in the Background section on the Capabilities tab. This will prevent didUpdatePushCredentials from being called!

The trick is you have to go in your plist, and in Required Background Modes you need to add App provides Voice over IP services.

I can't believe Apple has done this to us. I wasted an 8 hour work day looking for this simple fix.

For me the solution was to enable:

P.S. I didn't forget to enable But enabling general pushes was important too. So full code is:

import UIKit
import PushKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?


    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        voipRegistration()

        return true
    }

    // Register for VoIP notifications
    func voipRegistration() {
        let mainQueue = DispatchQueue.main
        // Create a push registry object
        let voipRegistry: PKPushRegistry = PKPushRegistry(queue: mainQueue)
        // Set the registry's delegate to self
        voipRegistry.delegate = self
        // Set the push type to VoIP
        voipRegistry.desiredPushTypes = [.voIP]
    }

}

extension AppDelegate: PKPushRegistryDelegate {
    func pushRegistry(_ registry: PKPushRegistry, didUpdate pushCredentials: PKPushCredentials, for type: PKPushType) {
        let token = pushCredentials.token.map { String(format: "%02.2hhx", $0) }.joined()
        print("voip token = \(token)")
    }

    func pushRegistry(_ registry: PKPushRegistry, didReceiveIncomingPushWith payload: PKPushPayload, for type: PKPushType) {
        print("payload = \(payload.dictionaryPayload)")
    }
}

Use below code and Make sure about following things.

**`**// Register for VoIP notifications**`**

- (void) voipRegistration {
    dispatch_queue_t mainQueue = dispatch_get_main_queue();
    // Create a push registry object
    _voipRegistry = [[PKPushRegistry alloc] initWithQueue: mainQueue];
    // Set the registry's delegate to self
    [_voipRegistry setDelegate:(id<PKPushRegistryDelegate> _Nullable)self];
    // Set the push type to VoIP
    _voipRegistry.desiredPushTypes = [NSSet setWithObject:PKPushTypeVoIP];
}

Call Below method in didFinishLaunchingWithOptions

Other deleget method as follow

- (void)pushRegistry:(PKPushRegistry *)registry didUpdatePushCredentials: (PKPushCredentials *)credentials forType:(NSString *)type {
    // Register VoIP push token (a property of PKPushCredentials) with server

    if([credentials.token length] == 0) {
        NSLog(@"voip token NULL");
        return;
    }
    NSLog(@"%@",credentials.token);
}

//Make sure about this in project capabilities

1)Background mode is ON

2)VOIP

3)Background Fetch

4)remotenotification

5) Dont forgot to import delegate

inside the Background MODE