Sample Dangerfile for iOS Project

Dangerfile

# PR is a work in progress and shouldn't be merged yet
warn "PR is classed as Work in Progress" if github.pr_title.include? "[WIP]"

# Warn when there is a big PR
warn "Big PR, consider splitting into smaller" if git.lines_of_code > 500

# Ensure a clean commits history
if git.commits.any? { |c| c.message =~ /^Merge branch '#{github.branch_for_base}'/ }
  fail "Please rebase to get rid of the merge commits in this PR"
end

# Mainly to encourage writing up some reasoning about the PR, rather than
# just leaving a title
if github.pr_body.length < 5
  fail "Please provide a summary in the Pull Request description"
end

# If these are all empty something has gone wrong, better to raise it in a comment
if git.modified_files.empty? && git.added_files.empty? && git.deleted_files.empty?
  fail "This PR has no changes at all, this is likely an issue during development."
end

has_app_changes = !git.modified_files.grep(/ProjectName/).empty?
has_test_changes = !git.modified_files.grep(/ProjectNameTests/).empty?

# If changes are more than 10 lines of code, tests need to be updated too
if has_app_changes && !has_test_changes && git.lines_of_code > 10
  fail("Tests were not updated", sticky: false)
end

# Info.plist file shouldn't change often. Leave warning if it changes.
is_plist_change = git.modified_files.sort == ["ProjectName/Info.plist"].sort

if !is_plist_change
  warn "Plist changed, don't forget to localize your plist values"
end

podfile_updated = !git.modified_files.grep(/Podfile/).empty?

# Leave warning, if Podfile changes
if podfile_updated
  warn "The `Podfile` was updated"
end

# This is swiftlint plugin. More info: https://github.com/ashfurrow/danger-swiftlint
#
# This lints all Swift files and leave comments in PR if 
# there is any issue with linting
swiftlint.lint_files inline_mode: true

It says Could not find gem 'swiftlint' in any of the gem sources listed in your Gemfile.