CocoaPods的安装步骤
一、什么是CocoaPods
CocoaPods是iOS项目的依赖管理工具，该项目源码在Github上管理。开发iOS项目不可避免地要使用第三方开源库，CocoaPods的出现使得我们可以节省设置和第三方开源库的时间。
在使用CocoaPods之前，开发项目需要用到第三方开源库的时候，我们需要
1.把开源库的源代码复制到项目中
2.添加一些依赖框架和动态库
3.设置-ObjC，-fno-objc-arc等参数
4.管理他们的更新
在使用CocoaPods后，我们只需要把用到的开源库放到一个名为Podfile的文件中，然后执行pod install.Cocoapods就会自动将这些第三方开源库的源码下载下来，并且为我们的工程设置好响应的系统依赖和编译参数。
二、CocoaPods的原理
CocoaPods的原理是将所有的依赖库都放到另一个名为Pods的项目中，然后让主项目依赖Pods项目，这样，源码管理工作都从主项目移到了Pods项目中。Pods项目最终会编译成一个名为libPods.a的文件，主项目只需要依赖这个.a文件即可。
三、CocoaPods的安装
CocoaPods可以方便地通过Mac自带的RubyGems安装。
打开Terminal，然后键入以下命令：（当出现-bash: pod: command not found提示时，需要重新安装CocoaPod）
sudo gem install cocoa pods 或 (sudo gem install -n/usr/local/bin cocoapods)
安装成功信息如下：
Successfully installed cocoapods-0.39.0
Parsing documentation for cocoapods-0.39.0
1 gem installed
Updating local specs repositories
CocoaPods 1.0.0.beta.8 is available.
To update use: `gem install cocoapods --pre`
[!] This is a test version we'd love you to try.
For more information see http://blog.cocoapods.org
and the CHANGELOG for this version http://git.io/BaH8pQ.
Analyzing dependencies
Downloading dependencies
Installing AFNetworking (3.0.4)
Generating Pods project
Integrating client project
[!] Please close any current Xcode sessions and use `XuHuiLifeCloud.xcworkspace` for this project from now on.
Sending stats
Pod installation complete! There is 1 dependency from the Podfile and 1 total
pod installed.
执行完这句如果报告以下错误：
ERROR: Could not find a valid gem 'cocoapods' (>= 0), here is why:
Unable to download data from https://rubygems.org/ - Errno::ETIMEDOUT: Operation timed out - connect(2) (https://rubygems.org/latest_specs.4.8.gz)
ERROR: Possible alternatives: cocoapods
或
ERROR: Could not find a valid gem 'cocoapods' (>= 0) in any repository
12306deMac-mini:~ a123456$ sudo gem install cocoapods
这是因为ruby的软件源rubygems.org因为使用亚马逊的云服务，被我天朝屏蔽了，需要更新一下ruby的源，过程如下：
步骤1：
在终端分别执行以下命令
gem sources -l (查看当前ruby的源)
gem sources --remove https://rubygems.org/ (或 sudo gem sources -r https://rubygems.org/ )
gem sources -a https://ruby.taobao.org/ （或 sudo gem sources -a http://ruby.taobao.org/ ）
gem sources -l
步骤2：
如果gem太老，可以尝试用如下命令升级gem，否则跳过该步骤2，可以先执行步骤3
sudo gem update --system
升级成功后会提示: RubyGems system software updated
步骤4：
然后重新执行安装下载命令
sudo gem install cocoapods
这时候应该没什么问题了
步骤5：
接下来进行安装，执行：
pod setup
Terminal会停留在 Setting up CocoaPods master repo 这个状态一段时间,是因为要进行下载安装,而且目录比较大,需要耐心等待一下.如果想加快速度,可使用cocoapods的镜像索引.（文章末尾附使用镜像索引的方法）
安装成功后,你会看到:
CocoaPods 1.0.0.beta.6 is available.
To update use: `gem install cocoapods --pre`
[!] This is a test version we'd love you to try.
For more information see http://blog.cocoapods.org
and the CHANGELOG for this version http://git.io/BaH8pQ.
Setup completed
四、CocoaPods在终端的安装过程信息
步骤1：
12306deMac-mini:~ a123456$ gem sources -l
*** CURRENT SOURCES ***
12306deMac-mini:~ a123456$ gem sources --remove https://rubygems.org/
source https://rubygems.org/ not present in cache
12306deMac-mini:~ a123456$ gem sources -a https://ruby.taobao.org/
https://ruby.taobao.org/ added to sources
12306deMac-mini:~ a123456$ gem sources -l
*** CURRENT SOURCES ***
https://ruby.taobao.org/
步骤3：
12306deMac-mini:~ a123456$ sudo gem install cocoapods
Password:在此输入密码，按回车
Fetching: i18n-0.7.0.gem (100%)
Successfully installed i18n-0.7.0
Fetching: thread_safe-0.3.5.gem (100%)
Successfully installed thread_safe-0.3.5
Fetching: tzinfo-1.2.2.gem (100%)
Successfully installed tzinfo-1.2.2
Fetching: minitest-5.8.4.gem (100%)
Successfully installed minitest-5.8.4
Fetching: activesupport-4.2.6.gem (100%)
Successfully installed activesupport-4.2.6
Fetching: nap-1.1.0.gem (100%)
Successfully installed nap-1.1.0
Fetching: fuzzy_match-2.0.4.gem (100%)
Successfully installed fuzzy_match-2.0.4
Fetching: cocoapods-core-0.39.0.gem (100%)
Successfully installed cocoapods-core-0.39.0
Fetching: claide-0.9.1.gem (100%)
Successfully installed claide-0.9.1
Fetching: colored-1.2.gem (100%)
Successfully installed colored-1.2
Fetching: xcodeproj-0.28.2.gem (100%)
Successfully installed xcodeproj-0.28.2
Fetching: cocoapods-downloader-0.9.3.gem (100%)
Successfully installed cocoapods-downloader-0.9.3
Fetching: cocoapods-plugins-0.4.2.gem (100%)
Successfully installed cocoapods-plugins-0.4.2
Fetching: cocoapods-search-0.1.0.gem (100%)
Successfully installed cocoapods-search-0.1.0
Fetching: cocoapods-stats-0.6.2.gem (100%)
Successfully installed cocoapods-stats-0.6.2
Fetching: cocoapods-try-0.5.1.gem (100%)
Successfully installed cocoapods-try-0.5.1
Fetching: netrc-0.7.8.gem (100%)
Successfully installed netrc-0.7.8
Fetching: cocoapods-trunk-0.6.4.gem (100%)
Successfully installed cocoapods-trunk-0.6.4
Fetching: molinillo-0.4.4.gem (100%)
Successfully installed molinillo-0.4.4
Fetching: escape-0.0.4.gem (100%)
Successfully installed escape-0.0.4
Fetching: cocoapods-0.39.0.gem (100%)
Successfully installed cocoapods-0.39.0
Parsing documentation for i18n-0.7.0
Installing ri documentation for i18n-0.7.0
Parsing documentation for thread_safe-0.3.5
Installing ri documentation for thread_safe-0.3.5
Parsing documentation for tzinfo-1.2.2
Installing ri documentation for tzinfo-1.2.2
Parsing documentation for minitest-5.8.4
Installing ri documentation for minitest-5.8.4
Parsing documentation for activesupport-4.2.6
unable to convert "\x84" from ASCII-8BIT to UTF-8 for lib/active_support/values/unicode_tables.dat, skipping
Installing ri documentation for activesupport-4.2.6
Parsing documentation for nap-1.1.0
Installing ri documentation for nap-1.1.0
Parsing documentation for fuzzy_match-2.0.4
Installing ri documentation for fuzzy_match-2.0.4
Parsing documentation for cocoapods-core-0.39.0
Installing ri documentation for cocoapods-core-0.39.0
Parsing documentation for claide-0.9.1
Installing ri documentation for claide-0.9.1
Parsing documentation for colored-1.2
Installing ri documentation for colored-1.2
Parsing documentation for xcodeproj-0.28.2
Installing ri documentation for xcodeproj-0.28.2
Parsing documentation for cocoapods-downloader-0.9.3
Installing ri documentation for cocoapods-downloader-0.9.3
Parsing documentation for cocoapods-plugins-0.4.2
Installing ri documentation for cocoapods-plugins-0.4.2
Parsing documentation for cocoapods-search-0.1.0
Installing ri documentation for cocoapods-search-0.1.0
Parsing documentation for cocoapods-stats-0.6.2
Installing ri documentation for cocoapods-stats-0.6.2
Parsing documentation for cocoapods-try-0.5.1
Installing ri documentation for cocoapods-try-0.5.1
Parsing documentation for netrc-0.7.8
Installing ri documentation for netrc-0.7.8
Parsing documentation for cocoapods-trunk-0.6.4
Installing ri documentation for cocoapods-trunk-0.6.4
Parsing documentation for molinillo-0.4.4
Installing ri documentation for molinillo-0.4.4
Parsing documentation for escape-0.0.4
Installing ri documentation for escape-0.0.4
Parsing documentation for cocoapods-0.39.0
Installing ri documentation for cocoapods-0.39.0
21 gems installed
步骤4：
12306deMac-mini:~ a123456$ pod setup
Setting up CocoaPods master repo
CocoaPods 1.0.0.beta.6 is available.
To update use: `gem install cocoapods --pre`
[!] This is a test version we'd love you to try.
For more information see http://blog.cocoapods.org
and the CHANGELOG for this version http://git.io/BaH8pQ.
Setup completed