title: Xcode error: "Failed to save .xcodeproj"
body: <p>I encountered an error message I have never seen before in Xcode. It is alerting me that it failed to save the project because it has been modified outside of Xcode. But as far as I know I did not modify it beyond the scope of Xcode.</p>
  
  <p><a href="https://i.stack.imgur.com/TDLRx.png" rel="noreferrer"><img src="https://i.stack.imgur.com/TDLRx.png" alt="enter image description here"></a></p>
  
  <p>I did recently perform a <code>pod install</code> to update some cocoa pods. That would be the only other modification to my project that I know of. That was some time ago before attempting to 'save', so I'm not sure it this is the problem.</p>
  
  <p><strong>QUESTION</strong></p>
  
  <p>How could my project be modified without my knowledge, and what would be the various results upon choosing to "<code>Keep Xcode Version</code>" or "<code>Read From Disk</code>"?</p>