Improve the implementation for on demand resources

CHANGELOG.md

@@ -3,7 +3,10 @@
 ## Master
 
 ##### Enhancements
-
+* Support On-Demand Resource   
+  [JunyiXie](https://github.com/JunyiXie)
+  [#issue_number](https://github.com/CocoaPods/Core/pull/622)
+
 * Add a post_integrate_hook API  
   [lucasmpaim](https://github.com/lucasmpaim)
   [#7432](https://github.com/CocoaPods/CocoaPods/issues/7432)

lib/cocoapods-core/specification/consumer.rb

@@ -110,9 +110,9 @@ def user_target_xcconfig
         merge_values(attr, value_for_attribute(:xcconfig), value_for_attribute(:user_target_xcconfig))
       end
 
-      # @return [Array<String>] A hash where the key represents the
-      #         paths of the on_demand_resources to copy and the values the paths of
-      #         the on_demand_resources that should be copied.
+      # @return [Hash{String=>String}]]  hash where the keys are the names of
+      #         the on demand resource and the values are their relative file
+      #         patterns.
       #
       spec_attr_accessor :on_demand_resources
 
@@ -479,6 +479,24 @@ def _prepare_resource_bundles(value)
         result
       end
 
+      # Ensures that the file patterns of the on demand resources are contained in
+      # an array.
+      #
+      # @param  [String, Array, Hash] value.
+      #         The value of the attribute as specified by the user.
+      #
+      # @return [Hash] the resources.
+      #
+      def _prepare_on_demand_resources(value)
+        result = {}
+        if value
+          value.each do |key, patterns|
+            result[key] = [*patterns].compact
+          end
+        end
+        result
+      end
+
       #-----------------------------------------------------------------------#
     end
   end

lib/cocoapods-core/specification/dsl.rb

@@ -1305,24 +1305,21 @@ def dependency=(args)
 
       # @!method on_demand_resources=(on_demand_resources)
       #
-      #   A list of on_demand_resources that should be copied into the target bundle.
+      #   A list of on_demand_resource that should be copied into the target bundle.
       #
       #   @example
       #
-      #     spec.on_demand_resources = 'Resources/HockeySDK.bundle'
-      #
-      #   @example
-      #
-      #     spec.on_demand_resources = ['Images/*.png', 'Sounds/*']
-      #
+      #   s.on_demand_resources = {
+      #       'Tag1' => ['file1.png', 'file2.png']
+      #   }
       #   @param  [String, Array<String>] resources
       #           The on_demand_resources shipped with the Pod.
       #
       attribute :on_demand_resources,
-                :container     => Array,
+                :types => [String, Array],
+                :container => Hash,
                 :file_patterns => true,
-                :singularize   => true
-
+                :singularize => true
 
       #------------------#