get the Ruby Source changed

sudo gem update --system

see the log below

Updating rubygems-update
Fetching: rubygems-update-2.6.7.gem (100%)
Successfully installed rubygems-update-2.6.7
Parsing documentation for rubygems-update-2.6.7
Installing ri documentation for rubygems-update-2.6.7
Installing darkfish documentation for rubygems-update-2.6.7
Installing RubyGems 2.6.7
RubyGems 2.6.7 installed
Parsing documentation for rubygems-2.6.7
Installing ri documentation for rubygems-2.6.7

=== 2.6.7 / 2016-09-26

Bug fixes:

* Install native extensions in the correct location when using the
  `--user-install` flag. Pull request #1683 by Noah Kantrowitz.
* When calling `Gem.sources`, load sources from `configuration`
  if present, else use the default sources. Pull request #1699
  by Luis Sagastume.
* Fail gracefully when attempting to redirect without a Location.
  Pull request #1711 by Samuel Giddins.
* Update vendored Molinillo to 0.5.1. Pull request #1714 by
  Samuel Giddins.

=== 2.6.6 / 2016-06-22

Bug fixes:

* Sort installed versions to make sure we install the latest version when
  running `gem update --system`. As a one-time fix, run
  `gem update --system=2.6.6`. Pull request #1601 by David Radcliffe.

=== 2.6.5 / 2016-06-21

Minor enhancements:

* Support for unified Integer in Ruby 2.4. Pull request #1618
  by SHIBATA Hiroshi.
* Update vendored Molinillo to 0.5.0 for performance improvements.
  Pull request #1638 by Samuel Giddins.

Bug fixes:

* Raise an explicit error if Signer#sign is called with no certs. Pull
  request #1605 by Daniel Berger.
* Update `update_bundled_ca_certificates` utility script for directory
  nesting. Pull request #1583 by James Wen.
* Fix broken symlink support in tar writer (+ fix broken test). Pull
  request #1578 by Cezary Baginski.
* Remove extension directory before (re-)installing. Pull request #1576
  by Jeremy Hinegardner.
* Regenerate test CA certificates with appropriate extensions. Pull
  request #1611 by rhenium.
* Rubygems does not terminate on failed file lock when not superuser. Pull
  request #1582 by Ellen Marie Dash.
* Fix tar headers with a 101 character name. Pull request #1612 by Paweł
  Tomulik.
* Add Gem.platform_defaults to allow implementations to override defaults.
  Pull request #1644 by Charles Oliver Nutter.
* Run Bundler tests on TravisCI. Pull request #1650 by Samuel Giddins.

=== 2.6.4 / 2016-04-26

Minor enhancements:

* Use Gem::Util::NULL_DEVICE instead of hard coded strings. Pull request #1588
  by Chris Charabaruk.
* Use File.symlink on MS Windows if supported. Pull request #1418
  by Nobuyoshi Nakada.

Bug fixes:

* Redact uri password from error output when gem fetch fails. Pull request
  #1565 by Brian Fletcher.
* Suppress warnings. Pull request #1594 by Nobuyoshi Nakada.
* Escape user-supplied content served on web pages by `gem server` to avoid
  potential XSS vulnerabilities. Samuel Giddins.

=== 2.6.3 / 2016-04-05

Minor enhancements:

* Lazily calculate Gem::LoadError exception messages. Pull request #1550
  by Aaron Patterson.
* New fastly cert. Pull request #1548 by David Radcliffe.
* Organize and cleanup SSL certs. Pull request #1555 by James Wen.
* [RubyGems] Make deprecation message for paths= more helpful. Pull
  request #1562 by Samuel Giddins.
* Show default gems when using "gem list". Pull request #1570 by Luis
  Sagastume.

Bug fixes:

* Stub ordering should be consistent regardless of how cache is populated.
  Pull request #1552 by Aaron Patterson.
* Handle cases when the @@stubs variable contains non-stubs. Pull request
  #1558 by Per Lundberg.
* Fix test on Windows for inconsistent temp path. Pull request #1554 by
  Hiroshi Shirosaki.
* Fix `Gem.find_spec_for_exe` picks oldest gem. Pull request #1566 by
  Shinichi Maeshima.
* [Owner] Fallback to email and userid when owner email is missing. Pull
  request #1569 by Samuel Giddins.
* [Installer] Handle nil existing executable. Pull request #1561 by Samuel
  Giddins.
* Allow two digit version numbers in the tests. Pull request #1575 by unak.

=== 2.6.2 / 2016-03-12

Bug fixes:

* Fix wrong version of gem activation for bin stub. Pull request #1527 by
  Aaron Patterson.
* Speed up gem activation failures. Pull request #1539 by Aaron Patterson.
* Fix platform sorting in the resolver. Pull request #1542 by Samuel E.
  Giddins.
* Ensure we unlock the monitor even if try_activate throws. Pull request
  #1538 by Charles Oliver Nutter.


=== 2.6.1 / 2016-02-28

Bug fixes:

* Ensure `default_path` and `home` are set for paths. Pull request #1513
  by Aaron Patterson.
* Restore but deprecate support for Array values on `Gem.paths=`. Pull
  request #1514 by Aaron Patterson.
* Fix invalid gem file preventing gem install from working. Pull request
  #1499 by Luis Sagastume.

=== 2.6.0 / 2016-02-26

Minor enhancements:

* RubyGems now defaults the `gem push` to the gem's "allowed_push_host"
  metadata setting.  Pull request #1486 by Josh Lane.
* Update bundled Molinillo to 0.4.3. Pull request #1493 by Samuel E. Giddins.
* Add version option to gem open command. Pull request #1483 by Hrvoje
  Šimić.
* Feature/add silent flag. Pull request #1455 by Luis Sagastume.
* Allow specifying gem requirements via env variables. Pull request #1472
  by Samuel E. Giddins.

Bug fixes:

* RubyGems now stores `gem push` credentials under the host you signed-in for.
  Pull request #1485 by Josh Lane.
* Move `coding` location to first line. Pull request #1471 by SHIBATA
  Hiroshi.
* [PathSupport] Handle a regexp path separator. Pull request #1469 by
  Samuel E. Giddins.
* Clean up the PathSupport object. Pull request #1094 by Aaron Patterson.
* Join with File::PATH_SEPARATOR in Gem.use_paths. Pull request #1476 by
  Samuel E. Giddins.
* Handle when the gem home and gem path arent set in the config file. Pull
  request #1478 by Samuel E. Giddins.
* Terminate TimeoutHandler. Pull request #1479 by Nobuyoshi Nakada.
* Remove redundant cache. Pull request #1482 by Eileen M. Uchitelle.
* Freeze `Gem::Version@segments` instance variable. Pull request #1487 by
  Ben Dean.
* Gem cleanup is trying to uninstall gems outside GEM_HOME and reporting
  an error after it tries. Pull request #1353 by Luis Sagastume.
* Avoid duplicated sources. Pull request #1489 by Luis Sagastume.
* Better description for quiet flag. Pull request #1491 by Luis Sagastume.
* Raise error if find_by_name returns with nil. Pull request #1494 by
  Zoltán Hegedüs.
* Find_files only from loaded_gems when using gemdeps. Pull request #1277
  by Michal Papis.


------------------------------------------------------------------------------

RubyGems installed the following executables:
    /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/gem

Ruby Interactive (ri) documentation was installed. ri is kind of like man 
pages for ruby libraries. You may access it like this:
  ri Classname
  ri Classname.class_method
  ri Classname#instance_method
If you do not wish to install this documentation in the future, use the
--no-document flag, or set it as the default in your ~/.gemrc file. See
'gem help env' for details.

RubyGems system software updated

install CocoaPods

find error below :

Fetching: nanaimo-0.2.3.gem (100%)
Successfully installed nanaimo-0.2.3
Fetching: colored2-3.1.2.gem (100%)
Successfully installed colored2-3.1.2
Fetching: claide-1.0.1.gem (100%)
Successfully installed claide-1.0.1
Fetching: CFPropertyList-2.3.5.gem (100%)
Successfully installed CFPropertyList-2.3.5
Fetching: xcodeproj-1.4.4.gem (100%)
ERROR:  While executing gem ... (Errno::EPERM)
    Operation not permitted - /usr/bin/xcodeproj

fix:
苹果系统升级OS X EL Capitan后会出现的插件错误，将安装流程 4.安装CocoaPods 的 (1)sudo gem install cocoapods ——>改为sudo gem install -n /usr/local/bin cocoapods

and it worked:

see below:

Successfully installed xcodeproj-1.4.4
Fetching: ruby-macho-1.1.0.gem (100%)
Successfully installed ruby-macho-1.1.0
Fetching: molinillo-0.5.7.gem (100%)
Successfully installed molinillo-0.5.7
Fetching: gh_inspector-1.0.3.gem (100%)
Successfully installed gh_inspector-1.0.3
Fetching: fourflusher-2.0.1.gem (100%)
Successfully installed fourflusher-2.0.1
Fetching: cocoapods-try-1.1.0.gem (100%)
Successfully installed cocoapods-try-1.1.0
Fetching: cocoapods-trunk-1.2.0.gem (100%)
Successfully installed cocoapods-trunk-1.2.0
Fetching: cocoapods-stats-1.0.0.gem (100%)
Successfully installed cocoapods-stats-1.0.0
Fetching: cocoapods-search-1.0.0.gem (100%)
Successfully installed cocoapods-search-1.0.0
Fetching: cocoapods-plugins-1.0.0.gem (100%)
Successfully installed cocoapods-plugins-1.0.0
Fetching: cocoapods-downloader-1.1.3.gem (100%)
Successfully installed cocoapods-downloader-1.1.3
Fetching: cocoapods-deintegrate-1.0.1.gem (100%)
Successfully installed cocoapods-deintegrate-1.0.1
Fetching: cocoapods-core-1.2.1.gem (100%)
Successfully installed cocoapods-core-1.2.1
Fetching: cocoapods-1.2.1.gem (100%)
Successfully installed cocoapods-1.2.1
Parsing documentation for xcodeproj-1.4.4
Installing ri documentation for xcodeproj-1.4.4
Parsing documentation for ruby-macho-1.1.0
Installing ri documentation for ruby-macho-1.1.0
Parsing documentation for molinillo-0.5.7
Installing ri documentation for molinillo-0.5.7
Parsing documentation for gh_inspector-1.0.3
Installing ri documentation for gh_inspector-1.0.3
Parsing documentation for fourflusher-2.0.1
Installing ri documentation for fourflusher-2.0.1
Parsing documentation for cocoapods-try-1.1.0
Installing ri documentation for cocoapods-try-1.1.0
Parsing documentation for cocoapods-trunk-1.2.0
Installing ri documentation for cocoapods-trunk-1.2.0
Parsing documentation for cocoapods-stats-1.0.0
Installing ri documentation for cocoapods-stats-1.0.0
Parsing documentation for cocoapods-search-1.0.0
Installing ri documentation for cocoapods-search-1.0.0
Parsing documentation for cocoapods-plugins-1.0.0
Installing ri documentation for cocoapods-plugins-1.0.0
Parsing documentation for cocoapods-downloader-1.1.3
Installing ri documentation for cocoapods-downloader-1.1.3
Parsing documentation for cocoapods-deintegrate-1.0.1
Installing ri documentation for cocoapods-deintegrate-1.0.1
Parsing documentation for cocoapods-core-1.2.1
Installing ri documentation for cocoapods-core-1.2.1
Parsing documentation for cocoapods-1.2.1
Installing ri documentation for cocoapods-1.2.1
14 gems installed

pod setup

pod setup

Setting up CocoaPods master repo
  $ /usr/bin/git clone https://github.com/CocoaPods/Specs.git master --progress
  Cloning into 'master'...
  remote: Counting objects: 1319185, done.        
  remote: Compressing objects: 100% (5666/5666), done.        
  Receiving objects:  46% (606826/1319185), 100.82 MiB | 2.42 MiB/s  

------------waiting----- then

Setting up CocoaPods master repo
  $ /usr/bin/git clone https://github.com/CocoaPods/Specs.git master --progress
  Cloning into 'master'...
  remote: Counting objects: 1319185, done.        
  remote: Compressing objects: 100% (5666/5666), done.        
  remote: Total 1319185 (delta 4465), reused 5340 (delta 2233), pack-reused 1310857        
  Receiving objects: 100% (1319185/1319185), 403.13 MiB | 1.58 MiB/s, done.
  Resolving deltas: 100% (657475/657475), done.
  Checking out files: 100% (160431/160431), done.
Setup completed