I was curious about the powerful features of mac 10.10, so I upgraded the system to 10.10. It turned out that the following problems occurred when using pods:
/System/Library/Frameworks//Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require': cannot load such file -- xcodeproj/prebuilt/universal.x86_64-darwin14-2.0.0/xcodeproj_ext (LoadError) from /System/Library/Frameworks//Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require' from /Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.17.0/lib/xcodeproj/:6:in `rescue in <top (required)>' from /Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.17.0/lib/xcodeproj/:3:in `<top (required)>' from /System/Library/Frameworks//Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require' from /System/Library/Frameworks//Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require' from /Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.17.0/lib/:30:in `<top (required)>' from /System/Library/Frameworks//Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require' from /System/Library/Frameworks//Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require' from /Library/Ruby/Gems/2.0.0/gems/cocoapods-0.33.1/lib/:2:in `<top (required)>' from /System/Library/Frameworks//Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require' from /System/Library/Frameworks//Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require' from /Library/Ruby/Gems/2.0.0/gems/cocoapods-0.33.1/bin/pod:32:in `<top (required)>' from /usr/bin/pod:23:in `load' from /usr/bin/pod:23:in `<main>'
After some random search, the specific solutions are as follows:
1. Open Xcode 6
2. Enter Preferences
3. Click the Locations option
4. Turn the Command Line Tools version into Xcode 6.0
5. Uninstall cocoapods and enter it in the terminal
$ sudo gem uninstall cocoapods
6. Install xcodeproj and enter it in the terminal
$ sudo gem install xcodeproj
7. Install cocoapods and enter it in the terminal
$ sudo gem install cocoapods
8. To test whether the pod is installed successfully, enter it in the terminal
$ pod --version