CocoaPods错误：CDN: trunk URL couldn't be downloaded:......(Connection refused

执行pod search时候出错：

$pod search YYWebImage

报错信息：

CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/4/c/8/YYWebImage/1.0.3/YYWebImage.podspec.json, error: Failed to open TCP connection to raw.githubusercontent.com:443 (Connection refused - connect(2) for "raw.githubusercontent.com" port 443)

实验发现，pod install和pod update也是这个样子，各种找，原因和解决方法 如下：

CocoaPods 1.8将CDN切换为默认的spec repo源，并附带一些增强功能！CDN支持最初是在1.7版本中引入的，最终在1.7.2中完成。 它旨在大大加快初始设置和依赖性分析。

目前电脑上安装的pods是1.8.4版本

$ pod --version

1.8.4

按照官方文档的指导，在项目podfile文件中添加source源：
source 'https://github.com/CocoaPods/Specs.git'
podfile文件中添加source源后，pod install和pod update可以正常操作，但是pod search有些库却仍旧不正常。

$ pod search mj
[!] CDN: trunk Repo update failed - 3 error(s):
CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/0/f/b/MJRefresh/0.0.1/MJRefresh.podspec.json, error: Operation timed out - SSL_connect
CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/0/f/b/MJRefresh/1.4.4/MJRefresh.podspec.json, error: Operation timed out - SSL_connect
CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/0/f/b/MJRefresh/2.4.9/MJRefresh.podspec.json, error: Operation timed out - SSL_connect

$ pod search rbtitle
-> RBTitleView (2.0.1)
   简单实用的titleView
   pod 'RBTitleView', '~> 2.0.1'
   - Homepage: https://github.com/RiberWang/RBTitleDemo
   - Source:   https://github.com/RiberWang/RBTitleDemo.git
   - Versions: 2.0.1, 1.0.1, 1.0.0 [master repo]

解决办法：

1. podfile文件中指定source源为master：

source 'https://github.com/CocoaPods/Specs.git'

2.执行pod repo remove trunk移除trunk源

执行完后，pod search就都正常了！

$ pod repo list

master
- Type: git (master)
- URL:  https://github.com/CocoaPods/Specs.git
- Path: /Users/Riber/.cocoapods/repos/master

trunk
- Type: CDN
- URL:  https://cdn.cocoapods.org/
- Path: /Users/Riber/.cocoapods/repos/trunk

2 repos
Ribers-Mac:ZNB_Country2.0 Riber$ pod repo remove trunk
Removing spec repo `trunk`

注意：podfile文件中一定要指定master源，因为现在默认是trunk源

source 'https://github.com/CocoaPods/Specs.git'

参考文章：

1. 官方说明
2. Github Issules