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 attac

Answer 1

I had similar issues when i installed XCode 4.5 on OS X Mountain Lion. I searched a while and tried some fixes but what finally solved the problem was adding "127.0.0.1 localhost" to my hosts file (/etc/hosts).

Here is what i have done:

Open a terminal shell with cmd+space > terminal
type in "cd /etc"
type in "sudo nano hosts"
type in your root password
add "127.0.0.1 localhost"
save with ctrl+o > return
close with ctrl+x
log out and log in again or restart

Answer 2

try to do next steps:

• Go to Product/Scheme/Edit Scheme then select Run section.
• Select Info Tan and set Debugger None.
• Run project. It must be working (without debugger)
• Go back to Edit Scheme and selecet debugger LLDB
• Run project. It is working.

Maybe additionally you need to delete derived data and do Product/Clean

Answer 3

Make sure you do not have an invalid build rule, that will cause this error, happened to me once (I had added a build rule by mistake and left it invalid).

Answer 4

Also make sure none of your file/group name collide with the projects default settings.

Things started breaking for me when I added an info.plist file to my project (Bad Idea). Same happens when you add a "Resource" Group. I don't have an exhaustive list, but if someone does please do share.

Cleaning out / Renaming these conflicting files and following the solution provided by Lindemann(https://stackoverflow.com/a/12504712/2069749) solved the problem for me.

Answer 5

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

Answer 6

If you are using a network account, you should replace the "~/Library/Application Support/iPhone Simulator" with a link to a local directory. This worked for me after trying everything else.