Lasso is an iOS application architecture for building discrete, composable and testable components both big and small - from single one-off screens, through complex flows, to high-level application structures.

Intro article sample code

This repository contains the sample code from the introductory articles:

Lasso: Introducing a new architectural framework for iOS

• LoginScreen.swift - the meat of the code from the article. Contains the complete module definition, store, and view controller.
• LoginService.swift - contains the service protocol and concrete conforming type used to log users in.
• LoginScreenTests.swift - contains all unit tests of the login screen. There's much more in here than was discussed in the article - most notably, there is some dependency injection that takes advantage of the Lasso @Mockable property wrapper.

Next steps

You may have noticed that when the user taps the login button, there is a delay before the store hears back from the service. During this delay, it is possible that the user could modify the information in the input fields or tap the login button again. How would you modify the store to prevent these from happening, and what should change in the view controller to accurately reflect this? Take a look at the login screen implementation in the main Lasso repository for one approach to solving this issue.

Lasso: An introduction to Flows

• TutorialFlow.swift
• TutorialScreen.swift

Xcode project files

The other files in the Xcode project are all in support of providing a small running app to see Lasso in action.

• AppDelegate.swift - every app needs one. This one just sets some colors and starts the AppFlow

• AppFlow.swift - simple class for controlling the high-level application flow, showing how to place the screens and start the flow:

  • Login -> Tutorial -> Content

• ContentScreen.swift - a placeholder for actual app content.

• The Extensions group contains some conveniences to pull as much of the common UIKit drudgery away from the important code.

The included Xcode project:

• requires Xcode 11.3
• compiles with Swift 5.1
• uses Swift package manager, to pull in the dependencies:
  • Lasso
  • WWLayout