digiacomo / coordinator_test

About The Project

Example project to illustrate Coordinator protocol.

Overview

Allow different frameworks (Feature1 and Feature2) to consume each other's user journeys without sharing concrete types with a simple and clear Dependency schema.

Environment.swift

Bare bone dependency injection based on Swift structs. The idea is to encapsulate all the dependencies required by a module to work in closures. Keep in mind this is just a streamlined injection mechanism. It can be replaced anytime.

Coordinator.swift

It's a Protocol to encapsulate any user journey based on the assumption that a User Journey (one or more set of screens) can be seen and consumed as a blackbox that requires an Input and returns one Output when the end is reached.

Example

In this example we have a Main target called Coordtest, a framework Common that has top level types and a couple of mock feature frameworks Feature1 and Feature2.

• Coordtest has visibility over Common, Feature1 and Feature2.
• Common has no visibility on anything
• Feature1 has visibility on Common only
• Feature2 has visibility on Common only

Feature1

contains Navigation implementation represented by MainCoordinator mock View and ViewModel

Feature2

contains Navigation implementation represented by ChildCoord mock View and ViewModel

The problem and solution

Navigation on MainCoordinator (Feature1) has a dependency on a ChildCoord (Feature2) however, we don't want to expose ChildCoord type to Feature1 as this would imply Feature2 to be visible to Feature1. Therefore the dependency is expressed as a Coordinator<Void, Void>. Which is a coordinator that takes no Input and Outputs nothing.

• The injection happens in CoordTest which is the only scope where we have visibility on Feature1 and 2 at the same time.
• We could be having any kind of Input and Output and in case we have multiple inputs we can use Tuples.

Closure syntactic sugar

Regular swift syntax can get in the way and make reading a bit difficult with these types therefore I've created a set of typealiases:

• typealias Closure<I, O> = (I) -> O
• typealias VoidClosure = () -> Void
• typealias VoidOutputClosure<I> = (I) -> Void
• typealias VoidInputClosure<O> = () -> O

This is because a Closure like this one: Closure<(UINavigationController, VoidClosure), AnyCoordinator<Void, Void>> In regular swift syntax would look like so: ((UINavigationController, VoidClosure)) -> AnyCoordinator<Void, Void>. Of course these are just typealiases. Not enforced in anyway anywhere.