Swift learning path
Build a practical understanding of swift learning path from the underlying principles.
LANGUAGE · 52 ARTICLES
Swift & Objective-C
Go beyond memorizing syntax and understand why the language rules exist, from fundamentals and memory to concurrency and the Objective-C runtime.
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Types and memory
Build a practical understanding of types and memory from the underlying principles.
Swift concurrency
Build a practical understanding of swift concurrency from the underlying principles.
Objective-C
Build a practical understanding of objective-c from the underlying principles.
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A guided path from fundamentals to the next step.
[Swift Basics #1] What Optionals Really Are and How to Unwrap Them
The first hurdle when learning Swift is optionals. The question mark in String?, if let, guard let, !, and ??. With so many forms of syntax, memorizing each separately can easily turn the rules into a jumble.
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[Swift Intermediate #1] Swift ARC Explained: Choose weak vs unowned by Lifetime
In the closures article, when we covered breaking retain cycles with [weak self], we left one question open. There is also unowned instead of weak—what is the difference, and when should you use it? To answer, we first need to look beneath the surface at how ARC actually works.
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[Advanced Swift #1] How async/await works: it’s not the thread that stops
At await, the function—not the thread—pauses. Here’s what suspension really means: the function stores its state on the heap and returns the thread to the cooperative pool, and why sequential await is not parallel execution.
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[Advanced Swift #9] Swift ABI Stability: Why App Sizes Shrank in 2019
App sizes shrank after Swift 5 and iOS 12.2 shipped in 2019, thanks to ABI stability. This article covers how the Swift runtime moved from every app into the OS, along with module stability and the trade-offs of @frozen.
Read articleSynchronous vs. Asynchronous, Blocking vs. Non-blocking — 2×2 Guide
Synchronous vs. asynchronous concerns who tracks task completion, while blocking vs. non-blocking concerns whether control is returned immediately. This guide explains why the two independent axes produce all four 2×2 combinations, with Swift examples.
Read article[Advanced Swift #8] ~Copyable, Ownership, and Noncopyable Types
Resources such as file handles and locks are meaningful only when unique, so they must not be copied. This guide explains how Swift 5.9’s ~Copyable encodes noncopyability in a type, covers borrowing, consuming, and inout, and clarifies where to use them.
Read article[Swift Deep Dive #7] Swift Macros Explained: The Truth Behind @Observable
Swift 5.9 macros are code-generation plugins embedded in the compiler. This overview covers how they receive syntax trees and return code, the freestanding (#) and attached (@) branches, and the cost of creating your own.
Read article[Swift Deep Dive #6] Swift Memory Layout: Property Order Changes Size
A struct's size is not a simple sum of its properties. This covers measured size, stride, alignment, padding, Optional's use of extra inhabitants, and 64-bit existential containers.
Read article[Advanced Swift #5] Swift dispatch: why final boosts performance
Method calls compile as direct calls, vtable lookups, or objc_msgSend. This article explains why final and private improve performance, the trap in protocol extensions, and how to verify it with a profiler.
Read articleKVO Internals Explained: The Truth Behind isa-Swizzling
The moment you attach an observer, KVO dynamically swaps the object's class with a subclass. This covers isa-swizzling, why class lies, and when notifications are not sent without going through the setter.
Read article[Advanced Swift #4] Structured Concurrency: Why You Shouldn't Open Tasks Carelessly
Structured concurrency answers who is responsible for ending asynchronous work. This article covers why child tasks cannot escape their parent scope, how cancellation propagates, and which guarantees you must manually reclaim with Task.detached.
Read article[Advanced Swift #3] Migrating Sendable and Swift 6 concurrency errors
Turning on Swift 6 mode unleashes concurrency errors, with Sendable at the center. This guide explains whether values may cross isolation boundaries and presents migration fixes in order: make them structs, make them immutable, or promote them to actors.
Read articleObjective-C Associated Objects: Adding Properties to Categories
Categories cannot add ivars, but Associated Objects let you attach values. This article explains the side table stored beside objects, a complete category-property implementation, and memory policies where assign requires care.
Read articleDelegate vs. Closure: 3 Criteria for Choosing a Callback
Delegates and closures handle the same callback needs, but they have different trade-offs. This article implements the same example side by side, distills five practical differences, and summarizes how to choose based on event count, relationship lifetime, and whether a return value is needed.
Read article[Advanced Swift #2] Swift actors: a complete guide to preventing data races
An actor is Swift’s fourth kind of type, protecting its own state. This guide explains how serialized access lets the compiler catch data races, including the classic reentrancy trap.
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