CocoaPods安装/搜索pod的错误

我正在尝试在我的项目中使用一些pod.但终端导致:

$ pod install
Analyzing dependencies
[!] Unable to find a specification for `Mantle`.

所以,我试图搜索pod或其他人以及我尝试过的任何pod,结果是:

$ pod search Mantle
[!] Unable to find a pod with name matching `Mantle'

$ pod search LBBlurredImage
[!] Unable to find a pod with name matching `LBBlurredImage'

怎么了？!该https://github.com/CocoaPods/Specs都豆荚....