pod install 突然报错 CDN: trunk Repo update failed - 2 error(s):
项目需要添加一个依赖库，但出现问题，如下：
[!] CDN: trunk Repo update failed - 2 error(s):
CDN: trunk URL couldn't be downloaded: https://cdn.jsdelivr.net/cocoa/Specs/8/5/c/mob_sharesdk/4.4.4/mob_sharesdk.podspec.json Response: Timeout was reached
CDN: trunk URL couldn't be downloaded: https://cdn.jsdelivr.net/cocoa/Specs/8/5/c/mob_sharesdk/4.4.5/mob_sharesdk.podspec.json Response: Timeout was reached
尝试很多个方法都无效，不是设置这里就是更新哪里。 最直接的方法：
pod repo remove trunk
然后更新项目的依赖库
pod install --repo-update
