iOS Builds fail with error "Seems to be a very old project file format - please open your project file in a more recent version of Xcode"

iOS builds including cordova-ios v4.5.5 or earlier will fail with this error in Appflow. This issue was corrected in cordova-ios v5.0.0. Updating to a current cordova-ios release will resolve the problem.

To remove and reinstall the iOS platform:

ionic cordova platform rm ios
ionic cordova platform add ios@5.1.1 
//the latest release of the current major version is recommended. This 
example specifies the latest version at the time of writing

see: cordova-ios

error text:

Seems to be a very old project file format 
- please open your project file in a more recent version of Xcode