MEComposeSessionHandler
An object that participates in the composition of mail messages, and annotates recipient tokens.
Declaration
@MainActor protocol MEComposeSessionHandler : NSObjectProtocolOverview
When the user composes a message, MailKit requests a compose session handler object from your extension. MailKit uses this handler in the following ways:
To inform it when the compose session begins and ends
To add status annotations for email addresses that the user enters into the To, Cc, and Bcc fields
To display a custom popover in the compose window
To include custom headers in an outgoing message
To confirm that an outgoing message is ready for delivery
Each of the items in the list above corresponds to methods that the handler implements.
To indicate that your extension contains a compose session handler, add MEComposeSessionHandler to the MEExtensionCapabilities array in the extension’s Info.plist file:
<key>NSExtensionAttributes</key>
<dict>
<key>MEExtensionCapabilities</key>
<array>
<string>MEComposeSessionHandler</string>
</array>
</dict>