Push Notification is not working (iOS)

iOS
17

The registerDevice() method response is not a deviceId but registrationId.
You can get deviceId this way:

- (void)application:(UIApplication *)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData*)deviceToken {
    [Backendless.shared.messaging registerDeviceWithDeviceToken:deviceToken responseHandler:^(NSString *registrationId) {
        NSLog(@"Device registration completed");
        NSLog(@"DeviceId = %@", Backendless.shared.messaging.currentDevice.deviceId);
    }];
}

This signature is from Swift-SDK but iOS-SDK has the same method.

Regards,
Olha