I’ve been keen on developing a Swedish BIP-39 compliant wordlist for some time now — using my favourite programming language Swift of course! A BIP-39 wordlist is a list of 2048 words that are easy to remember. In the context of BIP-39, each word can be used to encode a random integer in the range 0–2047 (11 bits). Where say the integer 3 is mapped to the fourth word in the wordlist. This can be used as a human-friendly serialization of random bytes, e.g. …

Did you read the first part?

This is the continuation of my previous article Single-Lince Controller: SLC, please read that before reading this, otherwise, the contents of this article won’t make any sense.

Advanced ViewModel

Let us have a look at a more complicated ViewModel and View, where we make use of the populate method. Let’s take a look at a simple SignIn scene implementation:

The view is simple, a usernameField and a passwordField that actually are some subclass of UITextFieldcapable of displaying validation error. For which we have some reactive property rx.validationfor toggling the result of the validation. We have a signInButton, which starts as disabled. arranged by a UIStackView. We also have some kind of LoadingView which is hidden by default and for which we have some reactive property rx.isLoading

TL;DR: In this article, I present the SLC: Single-Line ControllerUIViewController with a single line of code:


In this article, I present the core parts of a new iOS architecture I call the Single Line-Controller or SLC for short. Which is a derivation of MVVM but done right, because there is no ‘C’ in ‘MVVM’, right? Thus no room for the malicious Controller.

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Reference: Sundell’s tweet https://twitter.com/johnsundell/status/1014137138517102592

Disclaimer 1: This architecture is extremely custom. If you are a big fan of vanilla MVC will most likely detest what I present below.

Disclaimer 2: The code snippets presented below are made up revolving around the common use case — Authentication — thus it might contain typos or compilation errors. …

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Manual mapping of value types

Reflection in Swift is easy using the struct Mirror, with it we can inspect the names and types of properties in an instance of a struct or an instance of a class (soon you’ll see why it was important to bold the words).

Imagine we have a struct called Book which looks like this:

struct Book {
let title: String
let author: String?
let published: Date
let numberOfPages: Int
let chapterCount: Int?
let genres: [String]

Then we can create an instance of Book, let’s create Harry Potter!

let book = Book(title: "Harry Potter", author: "J.K. Rowling", published: Date(), numberOfPages: 450, chapterCount: 19, genres: ["Fantasy", "Best books…


Alexander Cyon

Cryptocurrency and DLT evangelist. Freelancing IT consultant and app developer in love with Swift.

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