Many thanks for your reply - The following was returned: infoDictionary nil WebDomain key value nil webDomain nil Could not initialize webDomain I guess I need to know what on earth info dictionary is and why it isn't populated - I'm a long time SQL Developer but new to XCODE and AWS so I may be asking very obvious questions! Earlier in the file, the following code seems to set info dictionary: let infoDictionaryMobileClient = AWSInfo.default().rootInfoDictionary["Auth"] as? [String: [String: Any]]         let infoDictionary: [String: Any]? = infoDictionaryMobileClient?["Default"]?["OAuth"] as? [String: Any]