This is due to a misconfiguration on Apple's DNS servers, documented at: https://github.com/keymanapp/keyman/issues/11061. We have an open feedbackassistant report for this.

This is a very late response but may help others, I hope! XCode sometimes gets confused -- particularly if you switch between multiple versions of source code. Delete DerivedData (check XCode | Preferences | Locations to find it), then do a clean build of your project. This can often help.