Sorting like Xcode. Fixes #615, with exceptions.

CHANGELOG.md

@@ -7,6 +7,10 @@
 * Updated latest SDK versions for the release of Xcode 10.2.  
   [Samuel Giddins](https://github.com/segiddins)
 
+* Sort by name like Xcode does.  
+  [Antoine Cœur](https://github.com/Coeur)
+  [#677](https://github.com/CocoaPods/Xcodeproj/pull/677)
+
 ##### Bug Fixes
 
 * Use modern localization identifier 'en' for the development region.  

lib/xcodeproj/project/object/group.rb

@@ -1,5 +1,6 @@
 require 'xcodeproj/project/object/helpers/groupable_helper'
 require 'xcodeproj/project/object/helpers/file_references_factory'
+require 'xcodeproj/project/object/helpers/sort_helper'
 
 module Xcodeproj
   class Project
@@ -437,10 +438,9 @@ def sort(options = nil)
                 next groups_position == :above ? 1 : -1
               end
             end
-
-            result = File.basename(x.display_name.downcase, '.*') <=> File.basename(y.display_name.downcase, '.*')
+            result = XcodeSortString.new(File.basename(x.display_name, '.*')) <=> XcodeSortString.new(File.basename(y.display_name, '.*'))
             if result.zero?
-              File.extname(x.display_name.downcase) <=> File.extname(y.display_name.downcase)
+              XcodeSortString.new(File.extname(x.display_name)) <=> XcodeSortString.new(File.extname(y.display_name))
             else
               result
             end

lib/xcodeproj/project/object/helpers/sort_helper.rb

@@ -0,0 +1,34 @@
+module Xcodeproj
+  # Wrapper for a string that sorts by name like Xcode does.
+  # @example
+  #   arrayOfFilenames.sort_by { |s| XcodeSortString.new(s) }
+  class XcodeSortString
+    include Comparable
+    attr_reader :str, :scrubbed, :ints_and_strings, :i_s_pattern
+
+    def initialize(str)
+      @str = str
+      @scrubbed = str.downcase
+      # `Integer`+`rescue`: credit to https://stackoverflow.com/a/39025521
+      @ints_and_strings = @scrubbed.scan(/\d+|\D+/).map { |s| begin Integer(s, 10); rescue ArgumentError; s end }
+      # comparing patterns: credit to https://rosettacode.org/wiki/Natural_sorting#Ruby
+      @i_s_pattern = @ints_and_strings.map { |el| el.is_a?(Integer) ? :i : :s }.join
+    end
+
+    def <=>(other)
+      if i_s_pattern.start_with?(other.i_s_pattern) || other.i_s_pattern.start_with?(i_s_pattern)
+        compare = ints_and_strings <=> other.ints_and_strings
+        if compare != 0
+          # we sort naturally
+          compare
+        else
+          # equality, we sort reverse raw
+          -(str <=> other.str)
+        end
+      else
+        # type mismatch, we sort alphabetically
+        scrubbed <=> other.scrubbed
+      end
+    end
+  end
+end

spec/project/object/helpers/sort_helper_spec.rb

@@ -0,0 +1,52 @@
+require File.expand_path('../../../../spec_helper', __FILE__)
+
+module ProjectSpecs
+  describe Xcodeproj::XcodeSortString do
+    before do
+      @helper = XcodeSortString
+    end
+
+    #-------------------------------------------------------------------------#
+
+    describe 'In general' do
+      it 'sorts names like Xcode' do
+        unsorted_names = [
+          # spaces comparison (test disabled: not properly supported)
+          # ' a', 'a ',
+          # basic mix
+          'a1', '1a',
+          # pure integers
+          '1', '2', '10', '01',
+          # multi integers
+          '0.1.1', '0.1.2', '0.1.10', '0.1.01',
+          # equal integers
+          'A1B001', 'A01B1',
+          # case comparison
+          'a', 'A'
+        ]
+        sorted = unsorted_names.sort_by { |s| @helper.new(s) }
+        # order given by Xcode 10.2 "Sort by Name" on macOS 10.14.4, English as primary language
+        sorted.should == [
+          # ' a',
+          '0.1.1',
+          '0.1.01',
+          '0.1.2',
+          '0.1.10',
+          '1',
+          '01',
+          '1a',
+          '2',
+          '10',
+          'a',
+          'A',
+          # 'a ',
+          'a1',
+          'A1B001',
+          'A01B1',
+        ]
+      end
+    end
+
+    #-------------------------------------------------------------------------#
+  end
+end