Titanium Invalid --ios-version value '5.0'

This can happen if you have either installed two different versions of Xcode in different locations in the past or chosen to install Xcode in a location that is different from the standard location.

First check the path where its pointing by below command
xcode-select -print-path 

 if this command gives any error like the below one then you need to set the path.
xcode-select: Error: Selected Xcode path (Xcode.app/Contents/Developer) is not a valid directory. Run xcode-select -switch to set the path to the Xcode folder.

To set the xcode path for titanium. 
sudo xcode-select -switch /Applications/Xcode.app/Contents/Developer/
Now Restart the Titanium