swiftformat pre-commit hook

pre-commit

#!/bin/bash

set -uo pipefail

status=0
tmp=$(mktemp)

script=$0

while read -r file; do
  swiftformat --config .swiftformat --lint "${file}" > /dev/null 2>&1
  file_status=$?
  if [[ ${file_status} -eq 1 ]]; then
    echo "${script}: swiftformat error: ${file}" >&2

    swiftformat --config .swiftformat "${file}" --output "${tmp}" > /dev/null 2>&1
    diff "${file}" "${tmp}"

    status=1
    echo
  elif [[ ${file_status} -gt 1 ]]; then
    # Run the command again to display the error
    swiftformat --config .swiftformat --lint "${file}" >&2
    exit ${file_status}
  fi
done < <(git diff --diff-filter=d --staged --name-only | grep '.swift$')

rm -f "${tmp}"

exit ${status}

Check only for changed files, and print the expected format when linting fails.