Please help in creating a message app filter extension for iPhone : I am developing a message filter app extension. 
I searched about it and got to know about identity lookup which is newly introduced concept in ios 11.0. 
I came to know that i have to insert keys in info.plist

    <key>NSExtension</key>
        <dict>
            <key>NSExtensionPrincipalClass</key>
                <string>MessageFilterExtension</string>
            <key>NSExtensionAttributes</key>
                <dict>
                    <key>ILMessageFilterExtensionNetworkURL</key>
                    <string>https://www.example-sms-filter-application.com/api</string>
                </dict>
            <key>NSExtensionPointIdentifier</key>
            <string>com.apple.identitylookup.message-filter</string>
         </dict>

but after inserting these, when in build app,  i am getting black screen.
I have just inserted this code only. nothing else in view controller.swift file and made a file MessageFilterExtension.swift with same class name.

Please help. 
Please look at these - https://developer.apple.com/documentation/identitylookup/creating_a_message_filter_app_extension