title: iOS Simulator crashes, device doesn't (dyld: Symbol not found)
body: <p>it took me some time to solve this so I thought if someone ever searches for it also they might find the solution here.</p>
  
  <p>The problem occurred when I had a framework called CoreUI. This worked fine on my iPhone and iPad but it crashes on the simulator with the following error to the terminal</p>
  
  <pre><code>dyld: Symbol not found: _OBJC_CLASS_$_CUICatalog
  Referenced from: /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk/System/Library/Frameworks/UIKit.framework/UIKit
  Expected in: /Users/sareninden/Library/Developer/Xcode/DerivedData/Treinplanner-bcfwuvntuwetsmavibxtvaiczpfg/Build/Products/Debug-iphonesimulator/CoreUI.framework/CoreUI
   in /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk/System/Library/Frameworks/UIKit.framework/UIKit
  </code></pre>
  
  <p>After looking through all the build settings and finding nothing I tried making an empty project with a framework called CoreUI. Without any logic added in it, it crashed with the same error.</p>
  
  <p>It appeared that in the simulator CoreUI is also a framework name used by Apple. Even though it was a swift only framework this still causes conflicts.</p>