Swift WTF: Weirdness, traps, and fixes

on YouTube ↗20m

" summary

Expect specifics: binary floating math shows 0.1 + 0.2 != 0.3 so use Swift Numeric or use a Decimal type for exactness; operator precedence makes -10^2 evaluate as -(10^2) so add parentheses to get (-10)^2; copying an implicitly unwrapped optional drops its IUO flag so treat it as a regular optional or stop using IUOs; Array syntax can create IndexPath when Foundation is present so comparative operators behave differently—use lexicographicallyPrecedes or make comparisons explicit; emoji flag replacement breaks with Objective‑C APIs, prefer Swift native string APIs.

AI-written summary · about

" chapters (7)

1. 0:00Swift WTF intro
2. 2:07Floating point surprises
3. 6:45Operator precedence pitfalls
4. 9:13Implicitly unwrapped optionals
5. 10:43Foundation array comparisons
6. 13:39Emoji flag replacement bug
7. 18:23Summary and help in Japan

" related talks

• 44mSo You Think You Know SwiftNick Lockwood · #Pragma Conference 2024
• 18mScientific SwiftJeff Biggus · dotSwift 2019
• 34mSo You Think You Know Swift?Nick Lockwood · ServerSide.swift 2024
• 25mSwift's Pointy Bits: Unsafe Swift & Pointer TypesNate Cook · try! Swift Tokyo 2017
• 05mThe Safety of Unsafe SwiftRay Fix · try! Swift Tokyo 2017
• 52mFunctional Programming and Polymorphism basics in SwiftTJ Usiyan · LambdaConf Winter Retreat 2017
• 40mLeveraging Swift’s Type SystemBenjamin Encz · 360|iDev 2016
• 53mSwift: New Paradigms for iOS DevelopmentMarc Prud'Hommeaux · GOTO Copenhagen 2014