pod install报错CDN: trunk URL couldn't be downloaded: https://cdn.jsdelivr.net/coc

如果本地缓存中有损坏的 podspec 文件，可能会导致问题。清理缓存后重试

rm -rf ~/Library/Caches/CocoaPods
rm -rf Pods
rm -rf ~/Library/Developer/Xcode/DerivedData/*
pod cache clean --all
pod install