Category: Software Dev

Software Dev

Results from builders 🧱

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Looking back, it’s interesting to appreciate the various Swift advancements that allowed SwiftUI to be created: namely opaque return types, property wrappers, and result builders.

It reminds me of all the things invented for the Apollo moon mission.

In particular, I’ve been appreciating result builders lately. They’re a useful, general-purpose feature on their own terms. I just created a cache-key builder at work which greatly simplified some pretty ugly and bug-prone logic for createing a cache key string.

I’ve seen a couple even more interesting result builds recently too.

👉 RequestDL, which simplifies the creation of network requests

👉 TextBuilder, which streamlines the creation of complex Text values

These are just two examples I’ve seen on iOS Dev Weekly once or twice, although I’m sure there are plenty more result builders out there to play with.

Software Dev

Super summary: Demystify SwiftUI

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Whenever I get stuck on a sticky problem in SwiftUI, I keep referring back to this great video from WWDC21 for context.

👉 Demystify SwiftUI

The video provides the bigger picture of how SwiftUI works with great analogies to the real world for better understanding.

I thought I’d give this video the super summary treatment to boil it down the most ideas that you can absorb at a quick glance. Refer to the full video 👆 for more info.

SwiftUI tracks three main concepts on a view

  • Identity
  • Lifetime and state
  • Dependencies 

Identity

Identity is how SwiftUI recognizes distinct elements throughout the view’s lifetime.

Identifiers should be stable and unique; it acts like a key.  Multiple views cannot share the same identifier.

Choosing a good identifier is your opportunity to control the lifetime of your view and data.

Types of identifiers

Explicit identifiers are like a dog name and are set with the id parameter. An explicit id is helpful if you want to refer to the view from other views.

Implied identifiers are an inherent identity based on the view’s structure, represented as if statements and other conditions in SwiftUI.

Lifetime and state

Lifetime tracks an existing view’s data over time. For example: the same cat (per identity) can be awake, asleep, annoyed, hungry, etc. over time.

Whenever identity changes, the state is replaced.

Dependencies

Dependencies are how SwiftUI understands when your UI needs to be updated.

Dependencies are the vars on the view, ie. Binding, State, Environment, ObservableObject, etc.

These data elements combine to create a dependency graph that SwiftUI uses to trigger view updates.

Tip

Inert modifiers are cheap and encouraged over branches (structurally different, separate implied identifier).

Software Dev

Clarity is (even) more important than brevity

patmcgLeave a comment

I have published a post or two about the powers of brevity. But we programmers sometimes take it too far.

Can someone tell me what these integers represent? 

case upc(Int, Int, Int, Int)

No? Me either.

This is how associated values are pretty much always done in Swift. But thanks to this post by Marco Eidinger via iOS Dev Weekly, I discovered something new and clarifying: it turns out that you can actually label your enum’s associated values too. People just don’t do it for some reason. 🤷🏻‍♂️

Can you tell me what the integers represent now?

case upc(numberSystem: Int, manufacturer: Int, product: Int, check: Int)

Isn’t that a little easier to understand?

I run into the assumption sometimes where people mistake brevity for efficiency. Brevity shouldn’t mean sacrificing valuable context for slightly fewer words. Thanks to the Marco Eidinger post for pointing this out explicitly. 👍

Clarity is more important than brevity.

Marco Eidinger