# webDomains Websites for the system to cover with a shielding view. ``` var webDomains: Set? { get set } ``` ## Discussion When the user visits a website in this list of domains, the system calls your extension that customizes the shield’s appearance. When the user taps on a button the shield displays, the system calls your extension that handles user actions. If your app doesn’t provide a list of domains to shield, this value is `nil`. Your app can shield up to 50 web domain tokens at once. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)