Add warnings and errors to xcode swift projects.

release_critical_warnings.sh

#!/usr/bin/env bash
# This work is based on answers in this Stack Overflow thread: http://stackoverflow.com/questions/24183812/swift-warning-equivalent

# Generates build warnings in non-release builds.
if [ "${CONFIGURATION}" != "Release" ]; then
    DEBUG_WARNING_TAGS="\/\/ TODO:|\/\/ FIXME:|\/\/ WARNING:|\/\/ CRITICAL:"
    find "${SRCROOT}" \( -name "*.h" -or -name "*.m" -or -name "*.swift" \) -print0 | xargs -0 egrep --with-filename --line-number --only-matching "($DEBUG_WARNING_TAGS).*\$" | perl -p -e "s/($DEBUG_WARNING_TAGS)/ warning: \$1/"
fi

# Generates build errors or warnings in Release
if [ "${CONFIGURATION}" = "Release" ]; then
    # TODO will still be considered a warning in Release builds
    RELEASE_WARNING_TAGS="\/\/ TODO:|\/\/ WARNING:"
    find "${SRCROOT}" \( -name "*.h" -or -name "*.m" -or -name "*.swift" \) -print0 | xargs -0 egrep --with-filename --line-number --only-matching "($RELEASE_WARNING_TAGS).*\$" | perl -p -e "s/($RELEASE_WARNING_TAGS)/ warning: \$1/"

    # FIXME and CRITICAL are errors in Release builds
    RELEASE_ERROR_TAGS="\/\/ FIXME:|\/\/ CRITICAL:"
    ERRORS_FOUND=0
    FIND_RESULT=( $(find "${SRCROOT}" \( -name "*.h" -or -name "*.m" -or -name "*.swift" \)) )

    # We must sequence each file individually, so we can detect if an error tag is present
    for FILEPATH in ${FIND_RESULT[*]}
    do
        GREP_RESULTS=$(egrep --with-filename --line-number --only-matching  "($RELEASE_ERROR_TAGS).*\$" $FILEPATH)

        # If GREP_RESULTS is not empty, then an error tag has been found. Output the errors, then flip ERRORS_FOUND
        if [ "$GREP_RESULTS" ]; then
            echo "$GREP_RESULTS" | perl -p -e "s/($RELEASE_ERROR_TAGS)/ error: \$1/"
            ERRORS_FOUND=1
        fi
    done

    # Errors that are outputted during the build do not actually cause the build to fail, so we must manually call exit 1
    if [ $ERRORS_FOUND = 1 ]; then
        exit 1
    fi
fi