I used to symbolicate the crash report in Xcode 5.1.1 directly as there was \"Symbolicate & Re-symbolicate\" in Devices section of Organiser. But after upgrading to Xcod
Connect the iOS device, open Devices (shift command 2), select the device and click 'View Device Logs'. On the left side bar, the crash logs will appear. Select the one you're interested in.
As long as you have archived the build that was running on the device at the time of the crash, the crash log will be symbolicated automatically after a few seconds. If not, right click the crash log and select 're-symbolicate log'.