[!] Unknown command: `SwiftSocket`

[Ferkelcode]

I typed : pod 'SwiftSocket' in Terminal, but return:

[!] Unknown command: SwiftSocket Did you mean: list?

Usage:

$ pod COMMAND

  CocoaPods, the Cocoa library package manager.

Commands:

+ cache         Manipulate the CocoaPods cache
+ deintegrate   Deintegrate CocoaPods from your project
+ env           Display pod environment
+ init          Generate a Podfile for the current directory
+ install       Install project dependencies according to versions from a
                Podfile.lock
+ ipc           Inter-process communication
+ lib           Develop pods
+ list          List pods
+ outdated      Show outdated project dependencies
+ plugins       Show available CocoaPods plugins
+ repo          Manage spec-repositories
+ search        Search for pods
+ setup         Setup the CocoaPods environment
+ spec          Manage pod specs
+ trunk         Interact with the CocoaPods API (e.g. publishing new specs)
+ try           Try a Pod!
+ update        Update outdated project dependencies and create new Podfile.lock

Options:

--allow-root    Allows CocoaPods to run as root
--silent        Show nothing
--version       Show the version of the tool
--verbose       Show more debugging information
--no-ansi       Show output without ANSI codes
--help          Show help banner of specified command

How can I install SwiftSocket?