New language, new programming paradigms. Since the release of Swift the Cocoa developer community is increasingly experimenting with functional programming. How can we adopt FP principles in real world applications? This talk will discuss how apps can make use of immutable value types to avoid common code smells and bugs. I will also discuss other benefits of a functional approach, such as modularity through function composition. Throughout the talk I will illustrate the architecture of a non-trivial iOS app that relies strongly on immutable value types. The main goal of this talk is to show pragmatic approaches for applying functional programming principles to common problems in Cocoa development.