Unable to add a source with url `https://github.com/CocoaPods/Specs.git` named `master-1`.

在pod install或pod update时出现如题的错误提示：

...

Setting up CocoaPods master repo
[!] Unable to add a source with url `https://github.com/CocoaPods/Specs.git` named `master-1`.
You can try adding it manually in `~/.cocoapods/repos` or via `pod repo add`.

错误的原因可能有很多种，其中有可能是升级了Xcode或是安装了新的Xcode，首先要让系统指定一个Xcode

xcode-select -p

输出：/Applications/Xcode.app/Contents/Developer

sudo xcode-select -switch /Applications/Xcode.app/

上面命令重新指定Xcode

---如果Xcode检查没有问题，上面命令可以不做，下面进入正题---

解决办法是：

1、进入/users/用户名/.cocoapods/repos，删除master文件夹
2、重新下载CocoaPods仓库

git clone https://git.coding.net/CocoaPods/Specs.git ~/.cocoapods/repos/master

当然你可以用下面方法（备用）
pod repo add master https://github.com/CocoaPods/Specs.git

下载仓库后如有必要pod setup一下

接下来就正常了