How to get SingleWSDL file from AX Web Service

I have created one AIF services with HTTP adapter in AX 2102 R3

This service is working fine.

We are developing Apple iOS app. so mobile developer requires this service in single WSDL file. When I click the singel WSDL im receiving the following error.

Service

The server was unable to process the request due to an internal error. For more information about the error, either turn on IncludeExceptionDetailInFaults (either from ServiceBehaviorAttribute or from the configuration behavior) on the server in order to send the exception information back to the client, or turn on tracing as per the Microsoft .NET Framework SDK documentation and inspect the server trace logs.

Can anyone help me how to get single WSDL file from AX web service for iOs app development,

Is there any other alternative way to provide the service to mobile app developer without using Azure.