Sometimes when you rename you app XCode4 hang while running app on simulator. And it stuck at “Attaching to ‘app name’ “. Here is the step how to fix it:
1. Clicking on the project name in the left pane (at the very top). This will bring up a new menu to the right, something like the project/ target editors in XCode4
2. Click on Target and Click on Build Settings up at the top.
3. Under Packaging make sure your product name is the same for every build, and equal to whatever it says it’s attaching to. Eg if XCode is Hanging at “Attaching to Lasso Tool” but your product name is “Alter Image” then it won’t build.
That was exactly my problem because I renamed my app half way through development.
!! Cheers !!