Are you building with PhoneGap Build or the CLI? If locally, what version of Xcode are you using? Also, what version of the Cordova Splash Screen plugin are you using?
Did you see my reply?
Try removing the splashscreen plugin and adding it back. If that doesn't work, remove the iOS platform and add it back to your project. (The latter assumes that you haven't made any changes to the Xcode project that can't safely be deleted by Cordova.)
can you tell me what this will do exactly?
do I remove the plugins and then do something - I can't see deleting them and putting them back will do anything?
The idea is to remove any corrupted plugin installs. The same is true if you need to rm/add a platform. Although one might imagine that nothing should change, I have found that there are occasions where that fixes the problem, and so it's pretty high up on the list of troubleshooting steps to try.