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

ios5 ios-simulator xcode4.3
larsschwegmann picture larsschwegmann · Mar 14, 2012 · Viewed 25.5k times · Source

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

Lindemann picture Lindemann · Sep 20, 2012

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

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