Adding swiftLint as a build step in CI (#486)

.github/workflows/ci.yml

@@ -1,6 +1,6 @@
 name: CI
 
-on: 
+on:
   push:
     branches:
       - main
@@ -13,6 +13,18 @@ on:
       - vnext-prototype
 
 jobs:
+  validation:
+    runs-on: macos-10.15
+    strategy:
+      fail-fast: true
+    steps:
+    - uses: actions/checkout@v2
+    - name: Switch to current version of Xcode
+      run: scripts/xcode_select_current_version.sh
+    - name: pod lib lint
+      run: scripts/podliblint.sh
+    - name: validation
+      run: scripts/validation.sh
   xcodebuild:
     runs-on: macos-10.15
     strategy:
@@ -35,9 +47,5 @@ jobs:
 
     steps:
     - uses: actions/checkout@v2
-    - name: Switch to current version of Xcode
-      run: scripts/xcode_select_current_version.sh
     - name: scripts/xcodebuild_wrapper.sh ${{ matrix.build_command }}
       run: scripts/xcodebuild_wrapper.sh ${{ matrix.build_command }}
-    - name: pod lib lint
-      run: scripts/podliblint.sh

.swiftlint.yml

@@ -99,7 +99,9 @@ whitelist_rules:
   - redundant_string_enum_value
 
   # Properties, variables, and constants should not have redundant type annotation
-  - redundant_type_annotation
+  # This rule is currently disabled because it invokes false warnings for Bool
+  # Github issue tracked on swift lint https://github.com/realm/SwiftLint/issues/3578
+  # - redundant_type_annotation
 
   # Returning Void in a function declaration is redundant.
   - redundant_void_return
@@ -166,9 +168,13 @@ whitelist_rules:
 
 included: # paths to include during linting. `--path` is ignored if present.
   - ${LINTPATH}
+  - ios
+  - macos
 
 excluded: # paths to ignore during linting. Takes precedence over `included`.
   - Pods
+  - tools
+
 explicit_type_interface: # requires type annotation on everything but local variables and constants
   excluded:
     - local

scripts/validation.sh

@@ -0,0 +1,7 @@
+# A simple script to validate project settings.
+
+if which swiftlint >/dev/null; then
+    swiftlint --config --strict .swiftlint.yml
+else
+    echo "warning: SwiftLint not installed, download from https://github.com/realm/SwiftLint"
+fi