title: UI API called from background thread in Swift 4 and running Firebase 4
body: <p>These are the errors that are currently present in my project after I downloaded the beta version of <strong>Xcode 9</strong>.</p>
  
  <p><a href="https://i.stack.imgur.com/zs11e.png" rel="noreferrer"><img src="https://i.stack.imgur.com/zs11e.png" alt="Error messages"></a></p>
  
  <p>This directly connects <a href="https://stackoverflow.com/questions/44391367/swift-4-uiapplication-registerforremotenotifications-must-be-called-from-mai">to this post.</a> In which similar problem is solved. I had this problem as well originally and fixed it by following the accepted solution. However, that did not fix these other error messages that I am getting.</p>
  
  <p>What is causing these? Are they a problem? How can I prevent them?</p>