#In your Xcode target project settings select the "Build phases" tab.
#Click the "+" button add select "New Run Script Phase"
#In the script area paste this tiny script which will increment the bundle version every time the project is built:

#!/bin/bash
# This script takes the build number from the release target plist, increments and then saves back
bN=$(/usr/libexec/PlistBuddy -c "Print CFBundleVersion" "${PRODUCT_SETTINGS_PATH}")
bN=$(($bN + 1))
/usr/libexec/PlistBuddy -c "Set :CFBundleVersion $bN" "${PRODUCT_SETTINGS_PATH}"