Why is my iOS Swift generated SDK missing a defaultClient member?

I ran through the Calc REST API tutorial given in the API Gateway guide and everything worked perfectly when I ran test invocations via the AWS Console. But when I generate the iOS Swift SDK from the deployed stage 'SDK Generation' tab, unzip and import into my Xcode project, the defaultClient member is missing in <API-Name>Client.swift.

The README.md file that comes with the SDK reads as follows:

# Use the SDK in your project

1. Grab the `defaultClient` from your code

        let client = <API-Name>Client.defaultClient()

1. You can now call your method using the client SDK

Does anyone know why this would be missing?