[Sandbox] Added #relativize_paths.

lib/cocoapods/sandbox.rb

@@ -103,6 +103,14 @@ module Pod
       result
     end
 
+    # Converts a list of paths to their relative variant.
+    #
+    # @return [Array<Pathname>] the relative paths.
+    #
+    def relativize_paths(paths)
+      paths.map { |path| relativize(path) }
+    end
+
     # @return [String] a string representation suitable for debugging.
     #
     def inspect

spec/unit/sandbox_spec.rb

@@ -51,6 +51,11 @@ module Pod
       @sandbox.relativize(path).should == expected
     end
 
+    it "converts a list of paths to the relative paths respec to the sandbox" do
+      paths = [temporary_directory + 'Sandbox/file_1', temporary_directory + 'Sandbox/file_2' ]
+      @sandbox.relativize_paths(paths).should == [Pathname.new('file_1'), Pathname.new('file_2')]
+    end
+
     #--------------------------------------#
 
     it "returns the path of the manifest" do