iOS Simulator crashes, device doesn't (dyld: Symbol not found)

Question

it took me some time to solve this so I thought if someone ever searches for it also they might find the solution here.

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

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

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.

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.

Answer 1

This is how DYLD_FRAMEWORK_PATH works. Because you have your own CoreUI.framework in your DYLD_FRAMEWORK_PATH, that one is used instead of the system one to satisfy the linkage from UIKit.framework.

Don't pick framework names that are used by system frameworks, ie:

ls $(xcrun --sdk iphonesimulator --show-sdk-path)/System/Library/*Frameworks

Answer 2

The solution is to not use module names (for your app or framework) that Apple uses. I found a list of frameworks here (https://github.com/jonathanpenn/ui-auto-monkey/issues/8). I do not know if it is complete but it is a good start.