具体错误：CDN: trunk Repo update failed - 18 error(s):
CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/2/7/4/YYModel/0.9.0/YYModel.podspec.json, error: Failed to open TCP connection to raw.githubusercontent.com:443 (Connection refused - connect(2) for "raw.githubusercontent.com" port 443)
CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/2/7/4/YYModel/0.9.1/YYModel.podspec.json, error: Failed to open TCP connection to raw.githubusercontent.com:443 (Connection refused - connect(2) for "raw.githubusercontent.com" port 443)
CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/2/7/4/YYModel/0.9.10/YYModel.podspec.json, error: Failed to open TCP connection to raw.githubusercontent.com:443 (Connection refused - connect(2) for "raw.githubusercontent.com" port 443)
CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/2/7/4/YYModel/0.9.11/YYModel.podspec.json, error: Failed to open TCP connection to raw.githubusercontent.com:443 (Connection refused - connect(2) for "raw.githubusercontent.com" port 443)
CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/2/7/4/YYModel/0.9.12/YYModel.podspec.json, error: Failed to open TCP connection to raw.githubusercontent.com:443 (Connection refused - connect(2) for "raw.githubusercontent.com" port 443)
CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/2/7/4/YYModel/0.9.2/YYModel.podspec.json, error: Failed to open TCP connection to raw.githubusercontent.com:443 (Connection refused - connect(2) for "raw.githubusercontent.com" port 443)
CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/2/7/4/YYModel/0.9.3/YYModel.podspec.json, error: Failed to open TCP connection to raw.githubusercontent.com:443 (Connection refused - connect(2) for "raw.githubusercontent.com" port 443)
CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/2/7/4/YYModel/0.9.4/YYModel.podspec.json, error: Connection reset by peer - SSL_connect
CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/2/7/4/YYModel/0.9.5/YYModel.podspec.json, error: Failed to open TCP connection to raw.githubusercontent.com:443 (Connection refused - connect(2) for "raw.githubusercontent.com" port 443)
Broken pipe - SSL_connect
CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/2/7/4/YYModel/0.9.7/YYModel.podspec.json, error: Failed to open TCP connection to raw.githubusercontent.com:443 (Connection refused - connect(2) for "raw.githubusercontent.com" port 443)
CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/2/7/4/YYModel/0.9.8/YYModel.podspec.json, error: Failed to open TCP connection to raw.githubusercontent.com:443 (Connection refused - connect(2) for "raw.githubusercontent.com" port 443)
CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/2/7/4/YYModel/0.9.9/YYModel.podspec.json, error: Failed to open TCP connection to raw.githubusercontent.com:443 (Connection refused - connect(2) for "raw.githubusercontent.com" port 443)
CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/2/7/4/YYModel/1.0/YYModel.podspec.json, error: Failed to open TCP connection to raw.githubusercontent.com:443 (Connection refused - connect(2) for "raw.githubusercontent.com" port 443)
CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/2/7/4/YYModel/1.0.1/YYModel.podspec.json, error: Failed to open TCP connection to raw.githubusercontent.com:443 (Connection refused - connect(2) for "raw.githubusercontent.com" port 443)
CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/2/7/4/YYModel/1.0.2/YYModel.podspec.json, error: Failed to open TCP connection to raw.githubusercontent.com:443 (Connection refused - connect(2) for "raw.githubusercontent.com" port 443)
CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/2/7/4/YYModel/1.0.3/YYModel.podspec.json, error: Failed to open TCP connection to raw.githubusercontent.com:443 (Connection refused - connect(2) for "raw.githubusercontent.com" port 443)
CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/2/7/4/YYModel/1.0.4/YYModel.podspec.json, error: Failed to open TCP connection to raw.githubusercontent.com:443 (Connection refused - connect(2) for "raw.githubusercontent.com" port 443)
错误原因：podfile文件中一定要指定master源，因为现在默认是trunk源，在podfile中指定官方仓库地址
source 'https://github.com/CocoaPods/Specs.git' #官方仓库地址
