Facebook provides the easiest way to track success of App Ads, implement powerful sharing or let people log into an app with Facebook. Among other tools, this SDK provides anonymized audience insight about the people interacting with the app as well as a way for people to login to the app through Facebook. It also contains five component SDKs that can be connected to individually.
Bolts is a collection of low-level libraries designed to make developing mobile apps easier. These libraries, originally created by Facebook and Parse, have been open sourced and made available to others without a mandatory Facebook developer or Parse affiliation. Bolts includes "tasks", which make organization of complex asynchronous code more manageable, and an implementation of the App Links Protocol, which helps link content in other apps.
Reactive X is the swift implementation of the Reactive programming language. Reactive X (RX) is a generic abstraction of computation expressed through the Observable <Element> interface. It is a extension for .Net