Author: Tina Holland

Swift’s standard library hands you Array, Set, and Dictionary—solid workhorses that cover most day-to-day needs. But the moment you reach for a ring buffer, a sorted bag, or a lazy evaluation pipeline, you’re staring down the barrel of a custom collection. A custom Swift collection is any type that conforms to the Collection protocol, inherits

Why Build Your Own Collection? Swift’s Array, Set, and Dictionary are workhorses. They’re fast, well-tested, and handle the vast majority of data storage tasks you’ll encounter. But sometimes, a general-purpose container doesn’t quite fit. Maybe you need a fixed-size window that automatically discards old data, or a structure that enforces strict ordering rules at the

You reach for Array, Set, and Dictionary without thinking. They’re the workhorses. But then you hit a data model that doesn’t slot into those shapes—maybe you’re wrapping a C pointer, juggling a sparse bitmap, or exposing a virtual view over a remote API. That’s when building a custom Swift collection stops being a theoretical detour

Every Swift developer has written a generic function, added @inlinable, or used a protocol witness, and then wondered: did the compiler actually do what I expected? Did it specialize the generic? Did it devirtualize the call? Did it eliminate the retain cycle I suspect is there? The Swift compiler’s intermediate representation—SIL, or Swift Intermediate Language—is

Swift’s standard library gives you Array, Set, and Dictionary right out of the box. They’re fast, well-tested, and handle most day-to-day tasks. But sometimes you hit a wall—maybe you need a fixed-capacity ring buffer for real-time audio, or a data structure that keeps elements in a specific order without the overhead of a full sort.

Swift property wrappers landed in Swift 5.1 with a clean promise: take repetitive property logic and package it into a reusable component. A @UserDefault wrapper reads and writes to UserDefaults. @Clamped keeps a number inside a range. @Trimmed strips whitespace from a string. The idea is sound. But in the years since, I’ve watched codebases

The Allure of Syntactic Sugar Swift property wrappers, introduced in Swift 5.1, are a clever bit of engineering. They let you abstract common property logic—like validation, persistence, or transformation—into a reusable component. Just slap @Clamped on a variable and its value stays within bounds. Use @UserDefault and your property syncs automatically with UserDefaults. It’s a

I still remember the first time I saw a Swift property wrapper in action. It was a neat little @UserDefault annotation that turned a tedious UserDefaults dance into a single line. The code looked cleaner, the intent was obvious, and I thought: this is the future of state management. That was 2019. Today, I spend

I still remember the first time I spotted a @UserDefault property wrapper in a code review. It was a tidy little annotation that promised to sweep away all the boilerplate of reading and writing to UserDefaults. The developer who added it was practically glowing. “Look how clean this is,” they said. And it was clean—on

Swift property wrappers landed in 2019 with a clean pitch: encapsulate repetitive property logic into a single, reusable annotation. The promise was seductive. Instead of scattering identical didSet observers or copy-pasting UserDefaults boilerplate across a dozen view models, you could just write @UserDefault and call it a day. Yuki Tanaka here, and I’ve watched this