1.Pods-XXXXX.debug.xcconfig.xcconfig: unable to open file 解决，2.升级CocoaPods到1.8.4，国内cdn源用不了

一、网上下载的工程都有这个问题  ：Pods-XXXXX.debug.xcconfig.xcconfig: unable to open file

解决办法很简单

1，sudo gem install cocoapods --pre

2，pod install

二、升级CocoaPods到1.8.4，国内cdn源用不了 

       执行 pod install 出现 ：

Cloning spec repo `trunk` from `https://cdn.cocoapods.org/`

[!] Unable to add a source with url `https://cdn.cocoapods.org/` named `trunk`.

You can try adding it manually in `/Users/weifulin/.cocoapods/repos` or via `pod repo add`.

解决办法：

        在Podfile文件中添加源' https://github.com/CocoaPods/Specs.git '

        然后执行pod install