# viewController(for:) Provides a custom view controller to display as part of the compose window. ``` func viewController(for session: MEComposeSession) -> MEExtensionViewController ``` ## Parameters `session` The session that represents the properties of the message in the compose window. ## Return Value A custom [`MEExtensionViewController`](/documentation/MailKit/MEExtensionViewController) subclass that Mail displays in the compose window. ## Discussion To configure an icon and tooltip for the compose session handler’s view controller, add the following entries to your extension’s `Info.plist` file: ```plist NSExtensionAttributes MEComposeSession MEComposeIcon YourCustomComposeIconName MEComposeIconToolTip Tooltip for the compose session handler. ``` Include an icon in your extension’s bundle using the name you specify for . > Tip: > Include the icon in an asset catalog in your extension’s bundle, and include both light and dark variants. --- 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)