Moving the folders around the inspector can cause the error "Build input file cannot be found"
SWIFT 5
In Swift 5, the error came up but the identity showed no errors.
For example [APPROJECTNAME]/[THEINFOPLISTFOLDER]/info.plist In the screenshot below, the path is API-client/Resources/info.plist
SWIFT 4
To fix it, go to the general tab and under identity reselect the info.plist that you like
I hope this helps