To resolve the issue of not being able to receive WhatsApp video calls on your Apple smartphone, follow these detailed steps:

1. Check Your Internet Connection
Ensure that you have a stable and strong Wi-Fi or mobile data connection. A weak signal can prevent WhatsApp from functioning properly, including video calls. You can try switching between Wi-Fi and mobile data to test the connectivity.

2. Update WhatsApp
Make sure you have the latest version of the WhatsApp app installed. Go to the App Store, search for WhatsApp, and tap "Update" if available. Keeping the app updated is essential for it to work correctly on your device - learn more.

3. Check App Permissions
Confirm that WhatsApp has the necessary permissions to access your microphone and camera. To do this:
- Open Settings on your iPhone.
- Scroll down and tap on WhatsApp.
- Ensure that permissions for the Camera and Microphone are enabled.

4. Disable Silent Mode
If your phone is on silent mode, you might not receive alerts for incoming calls. Switch off silent mode by toggling the switch on the side of your device to ensure calls can alert you - learn more.

5. Force Quit and Restart WhatsApp
To refresh the app, force quit WhatsApp and then open it again:
- Swipe up from the bottom of the screen (or double-tap the Home button) to view the app switcher.
- Find WhatsApp and swipe it up to close it.
- Then, reopen WhatsApp and try receiving the video call again - learn more.

6. Restart Your iPhone
Restarting your device can resolve many small software issues:
- Hold the power button and either volume button until the slider appears.
- Slide to power off, wait a few moments, then turn your iPhone back on.

7. Ensure Your iOS is Updated
Make sure your iPhone is running the latest version of iOS. Go to Settings > General > Software Update and install any available updates. Compatibility with WhatsApp is critical, especially after major iOS updates - learn more.

8. Reset Network Settings
If issues persist, you might need to reset your network settings. This will remove all saved Wi-Fi passwords, so make sure you have those handy:
- Go to Settings > General > Reset > Reset Network Settings.

If after trying all these steps you're still unable to receive video calls, consider reinstalling WhatsApp. Uninstall the app and then reinstall it from the App Store. Make sure to back up your chats before doing so to avoid data loss - learn more.

Following these steps should help you resolve the issue with receiving video calls on WhatsApp. If problems continue, you may want to reach out to WhatsApp support for further assistance.