The Apple Developer Forum has a thread, https://devforums.apple.com/message/1010068#1010068 , which describes how to diagnose this problem. I had his problem for Xcode 6 GM Seed, in particular version 6.0.1 (6A317). This is not necessarily a solution, but it may help some people get a better diagnosis.
Useful steps are as follows:
1) Create or modify your ~/.lldbinit and add log enable -f /tmp/lldb-api.txt lldb api to it.
2) Restart the debugger session (no need to restart Xcode or something else)
3) Check the file in /tmp/lldb-api.txt . Find the line starting with SBDebugger::CreateTarget(...) . Mine looked something like this.
SBDebugger (0x7f83671fd600) :: CreateTarget (File Name = "/Users/xxxxxxxx/Library/Developer/Xcode/DerivedData/Dino-gjuxikhuyokkqufeqmesmgjcxylu/Build/Products/Debug-iphones_8664_phlim_name ), add_dependent_modules = 1, error = the specified architecture "x86_64" is incompatible with 'i386-apple-ios' in' / Users / xxxxxxx / Library / Developer / Xcode / DerivedData / Dino-gjuxikhuyokkqufeqmesmgjcxylu / Build / Products / Debug-iphonesimulator .app / Dino ') => SBTarget (0x0)
4) Inspect the target file from the above output log, in my case -
file "/Users/xxxxxxx/Library/Developer/Xcode/DerivedData/Dino-gjuxikhuyokkqufeqmesmgjcxylu/Build/Products/Debug-iphonesimulator/Dino.app/Dino"
/Users/apanagar/Library/Developer/Xcode/DerivedData/Dino-gjuxikhuyokkqufeqmesmgjcxylu/Build/Products/Debug-iphonesimulator/Dino.app/Dino: Mach-O i386 executable
5) So, in my case, my problem was the architecture for which I was building. The target architecture for your project should match the line in the line SBDebugger :: CreateTarget () in the output log file.
The Xcode document points to the following. I had to go through my nested framework and change some outdated architecture goals -
NOTE ON 64-BIT ARCHITECTURE
The goal of the application extension is to include the arm64 architecture in its architecture creates the settings or it will be rejected by the App Store. Xcode includes this architecture with its “Standard architectures” when you create a new goal for expanding your application.
If your supporting targeted app links are included in the embedded infrastructure, the app must also include the arm64 architecture, or it will be rejected by the App Store.
For more information about 64-bit development, see the 64-Bit Migration Guide Cocoa Touch Guide or the 64-Bit Migration Guide for Cocoa, depending on your target platform.
https://developer.apple.com/library/ios/documentation/General/Conceptual/ExtensibilityPG/ExtensionCreation.html#//apple_ref/doc/uid/TP40014214-CH5-SW1