MBL-2782: Add swiftlint and run automatically with Danger (#2625)

Author: amy-at-kickstarter

.swiftlint.yml

@@ -0,0 +1,22 @@
+disabled_rules:
+  # It's OK to have a TODO across PRs.
+  - todo
+  # It's OK to have a force try.
+  - force_try
+  # These are all whitespace rules.
+  # swiftformat handles all our whitespace.
+  - line_length
+  - colon
+  - comma
+  - comment_spacing
+
+# Setting up swiftlint on 9/15/25.
+# We only want to catch future violations, so creating a baseline.
+baseline: swiftlint_baseline_09_15_2025.json
+
+opt_in_rules:
+  - closure_body_length
+
+excluded:
+  # GraphAPI is autogenerated
+  - GraphAPI

Dangerfile

@@ -5,4 +5,10 @@ warn("Big PR") if git.lines_of_code > 500
 swiftformat.additional_message = "This PR violates our formatting conventions. Run ./bin/format.sh to fix."
 swiftformat.binary_path = "bin/swiftformat"
 swiftformat.additional_args = "--config .swiftformat --swiftversion 5"
-swiftformat.check_format(fail_on_error: true)
+swiftformat.check_format(fail_on_error: true)
+
+# SwiftLint
+swiftlint.binary_path = "bin/swiftlint"
+swiftlint.config_file = ".swiftlint.yml"
+swiftlint.max_num_violations = 20
+swiftlint.lint_files