Notification preferences can easily be managed in your WhatsApp settings. iPhone will automatically display a push notification to alert you of an incoming message.
iOS apps can provide three types of notifications:
To make changes to your notification preferences:
Open WhatsApp > tap Settings> Notifications. Review that Show Notifications is enabled for Message and Group Notifications.
You can turn off the vibration or sounds you experience in the app. Open WhatsApp > Settings > Notifications > In-App Notifications.
Make sure that your notification settings are turned on in both your WhatsApp and iPhone settings.
If you’ve verified that your notification settings are correct and you’re still not receiving notifications, this is likely an issue with your connection or iOS.
Please note that delivery of notifications is controlled entirely by Apple's Push Notification Service (APNS), and WhatsApp has no way to resolve issues with this service. If someone sends you a message while you’re offline, that message will be sent to APNS to be delivered to your phone. WhatsApp doesn’t have control or visibility over the delivery of these notifications. The issue may be presenting itself in WhatsApp, but the issue derives from APNS or the iOS.
Typically, the only way to resolve this issue is to restore your phone to factory settings and set the phone up as new.
Note: If you restore a backup, you’ll likely restore the issue as well. Push notifications require a valid SIM card and an active Wi-Fi or cellular connection.