What is the crash of "The app's Info.plist must contain an NSPhotoLibraryAddUsageDescription"? : <p>I faced the following error (iOS 11):</p>

<blockquote>
  <p>This app has crashed because it attempted to access privacy-sensitive
  data without a usage description.  The app's Info.plist must contain
  an <code>NSPhotoLibraryAddUsageDescription</code> key with a string value
  explaining to the user how the app uses this data.</p>
</blockquote>

<p>Note that although the application <em>info.plist</em> does contains <code>NSPhotoLibraryUsageDescription</code> it still crashes, why?</p>
