title: Unsupported swift version (SWIFT 5)
body: <p>before you mark this question as a duplicate, I checked <a href="https://stackoverflow.com/questions/55366024/how-to-fix-swift-version-3-0-is-unsupported-supported-versions-are-4-0-4-2">this question</a></p>
  
  <p>and it didn't work for me. </p>
  
  <p>how to fix this error:</p>
  
  <pre><code>error: SWIFT_VERSION '5.0' is unsupported, supported versions are: 3.0, 4.0, 4.2. (in target 'DropDown')
  </code></pre>