Add ios_get_build_number action

CHANGELOG.md

@@ -10,6 +10,8 @@ _None_
 
 ### New Features
 
+- Add `ios_get_build_number` action to get the current build number from an `xcconfig` file. [#458]
+
 _None_
 
 ### Bug Fixes

lib/fastlane/plugin/wpmreleasetoolkit/actions/ios/ios_get_build_number.rb

@@ -0,0 +1,47 @@
+module Fastlane
+  module Actions
+    class IosGetBuildNumberAction < Action
+      def self.run(params)
+        require_relative '../../helper/ios/ios_version_helper'
+
+        UI.user_error!('You need to set at least the PUBLIC_CONFIG_FILE env var to the path to the public xcconfig file') unless ENV['PUBLIC_CONFIG_FILE']
+
+        Fastlane::Helper::Ios::VersionHelper.get_build_number
+      end
+
+      #####################################################
+      # @!group Documentation
+      #####################################################
+
+      def self.description
+        'Gets the public build number of the app'
+      end
+
+      def self.details
+        'Gets the public build number of the app'
+      end
+
+      def self.available_options
+        # Define all options your action supports.
+      end
+
+      def self.output
+        # Define the shared values you are going to provide
+      end
+
+      def self.return_value
+        # If you method provides a return value, you can describe here what it does
+        'Return the public build number of the app'
+      end
+
+      def self.authors
+        # So no one will ever forget your contribution to fastlane :) You are awesome btw!
+        ['Automattic']
+      end
+
+      def self.is_supported?(platform)
+        [:ios, :mac].include?(platform)
+      end
+    end
+  end
+end

lib/fastlane/plugin/wpmreleasetoolkit/helper/ios/ios_version_helper.rb

@@ -180,6 +180,14 @@ def self.get_internal_version
           get_version_strings()[1]
         end
 
+        # Returns the current value of the `BUILD_NUMBER` key from the public xcconfig file
+        #
+        # @return [String] The current build number according to the public xcconfig file.
+        #
+        def self.get_build_number
+          read_build_number_from_config_file(ENV['PUBLIC_CONFIG_FILE'])
+        end
+
         # Prints the current and next release version numbers to stdout, then return the next release version
         #
         # @return [String] The next release version to use after bumping the currently used public version.