# webDomainCategories Categories of websites for the system to cover with a shielding view. ``` var webDomainCategories: ShieldSettings.ActivityCategoryPolicy? { get set } ``` ## Discussion When the user visits a website in one of these categories, 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 website categories to shield, this value is `nil`. Your app can shield up to 50 category tokens and specify up to 50 web domain tokens exceptions 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)