Installer

The Installer is responsible of taking a Podfile and transform it in the Pods libraries. It also integrates the user project so the Pods libraries can be used out of the box.

The Installer is capable of doing incremental updates to an existing Pod installation.

The Installer gets the information that it needs mainly from 3 files:

Podfile: The specification written by the user that contains information about targets and Pods.
Podfile.lock: Contains information about the pods that were previously installed and in concert with the Podfile provides information about which specific version of a Pod should be installed. This file is ignored in update mode.
Manifest.lock: A file contained in the Pods folder that keeps track of the pods installed in the local machine. This files is used once the exact versions of the Pods has been computed to detect if that version is already installed. This file is not intended to be kept under source control and is a copy of the Podfile.lock.

The Installer is designed to work in environments where the Podfile folder is under source control and environments where it is not. The rest of the files, like the user project and the workspace are assumed to be under source control.