ios5 - Xcode compiles my App, but can't run it in the simulator

Question

when i compile my app, Xcode just says "Attaching to Projectname..." and gets stuck there. The debugger just prints this out:

error: failed to attach to process ID 0

I tried to clean & build again and it still doesn't work out. I googled but couldn't find anything helpful. How can I fix this problem? Thank You!

Answer 1

The solution for me was to delete everything Xcode has generated earlier:

• the App on the Simulator...if this is not possible because you cant reach the Homescreen, you can delete the App directly under ~/Library/Application Support/iPhoneSimulator/6.0/Applications
• delete the Derived Data in the Organizer under Projects or directly in ~/Library/Developer/Xcode/DerivedData
• clean the Build Folder by choosing "Product" in the MenuBar and click while you press the Alt-key on "Clean Build Folder"
• Restart Xcode