Unable to install Cocoapods on Yosemite DP 7 - objective-c

Question

I am having trouble installing Cocoapods on Yosemite DP 7 installed on a separate partition. I already attempted following the instructions found on Cocoapods with Xcode 6 and 10.10 Yosemite and in the issue(https://github.com/CocoaPods/CocoaPods/issues/2219) closed due to the same solution proposed on the Stack Overflow link.
I continue to get the following error:
Rasmuss-MacBook-Pro:~ rasmusth$ sudo gem install cocoapods
Building native extensions. This could take a while...
ERROR: Error installing cocoapods:
ERROR: Failed to build gem native extension.
"/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby" -rubygems /Library/Ruby/Gems/2.0.0/gems/rake-0.9.6/bin/rake RUBYARCHDIR=/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.17.0/ext RUBYLIBDIR=/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.17.0/ext
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby extconf.rb
checking for -std=c99 option to compiler... *** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers. Check the mkmf.log file for more details. You may
need configuration options.
Provided configuration options:
--with-opt-dir
--without-opt-dir
--with-opt-include
--without-opt-include=${opt-dir}/include
--with-opt-lib
--without-opt-lib=${opt-dir}/lib
--with-make-prog
--without-make-prog
--srcdir=.
--curdir
--ruby=/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:434:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:549:in `block in try_compile'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:502:in `with_werror'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:549:in `try_compile'
from extconf.rb:24:in `block in <main>'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:895:in `block in checking_for'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:340:in `block (2 levels) in postpone'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:310:in `open'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:340:in `block in postpone'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:310:in `open'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:336:in `postpone'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:894:in `checking_for'
from extconf.rb:23:in `<main>'
rake aborted!
Command failed with status (1): [/System/Library/Frameworks/Ruby.framework/...]
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.17.0/ext/xcodeproj/Rakefile:37:in `block in <top (required)>'
Tasks: TOP => default => ext
(See full trace by running task with --trace)
Gem files will remain installed in /Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.17.0 for inspection.
Results logged to /Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.17.0/ext/xcodeproj/gem_make.out
I am suspecting that this may have to do with the fact that I have Yosemite on a separate partition, but otherwise I am clueless.

Answer 1

I ran into the same issue. After much hair pulling following the same steps as everyone else, the following worked.
$ xcode-select --install (to confirm command line tools are installed)
Installed nvm stable (and homebrew): $ \curl -sSL https://get.rvm.io | bash -s stable
close/reopen terminal
Installed ruby 2.1.2: $ rvm install 2.1
Switch to it: $ rvm use 2.1
Uninstall/reinstall xcodeproj and cocoapods

Answer 2

Xcode 6.0 GM is missing the 10.10 SDK and therefore the gem xcodeproj can't be compiled which has some C code in it which needs the 10.10 SDK.
This is going to be fixed in the future.
For now you can work around it like this:
Terminal: sudo gem uninstall cocoapods xcodeproj
Download Xcode 6.1 (right now Beta 2 is the current one)
Start it go to Settings -> Location -> Command Line Tools -> Change to Xcode 6.1 Beta
Terminal: sudo gem install cocoapods
Change your Command Line tools back to GM (if you want/need)
For more information see: https://github.com/CocoaPods/CocoaPods/issues/2432