title: Module iCloudStorage requires main queue setup since it overrides `constantsToExport`
body: <p>When launching my iOS App built with react-native, I get the following warning:</p>
  <blockquote>
  <p>Module iCloudStorage requires main queue setup since it overrides
  <code>constantsToExport</code> but doesn't implement <code>requiresMainQueueSetup</code>. In
  a future release React Native will default to initializing all native
  modules on a background thread unless explicitly opted-out of.</p>
  </blockquote>
  <p>I've been searching around to find a solution but the only thing I found was this:</p>
  <blockquote>
  <p>add requiresMainQueueSetup to prevent warning and future side-effects
  in RCCManagerModule</p>
  </blockquote>
  <p>It says I should add the following snippet to <code>ios/RCCManagerModule.m</code></p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>(BOOL)requiresMainQueueSetup
  {
      return YES;
  }</code></pre>
  </div>
  </div>
  </p>
  <p>There is <strong>no</strong> <code>RCCManagerModule.m</code> file in my react-native project.</p>
  <p>Is there any other solution to this?</p>
  <p>And if possible, could someone explain me what does this error actually says/means: what is main queue setup in this context?</p>