The answer is
I know that this is not a technical solution but I had my iphone connected with the computer by cable and disconnecting the device from the computer and connecting it again (by cable again) worked for me as I could not solved it with the solutions that are provided before.
In Xcode Version 6.1.1 (6A2008a), after "Processing Symbol Files", a folder containing symbols associated with the device (including iOS version and CPU type) was created in ~/Library/Developer/Xcode/iOS DeviceSupport/ like this:
Add SDK version correspond to your iPhone iOS, eg: iOS 10.3
path:
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport
It's downloading. When it's finished, it's OK. As shown in the figure:
In my case symbolicating was take forever. I force restart my phone with both of on/off and home button. Now quickly finished symbolicating and I am starting run my app via xcode.
It compares crash logs retrieved from the device to archived (symbolized to be correct) version of your applications to try to retrieved where on your code the crash occurred.
Look at xcode symbol file location for details
Annoying error. I solved it by plugging the cable directly into the iPad. For some reason the process would never finish if I had the iPad in Apple's pass-through stand.
xCode just copy all crashes logs. If you want to speed-up: delete number of crash reports after you analyze it, directly in this window.
Devices -> View Device Logs -> All Logs
Source: Stackoverflow.com