Scott Berrevoets • 4/24/2026

Objective-C enums can be string-backed... sort of

This article examines the use of FourCC (four-character code) constants in Objective-C enums, specifically using AVAudioSessionErrorCode as an example. It explains how multi-character constants like 'msrv' or 'siri' are actually integers derived from ASCII byte values, not true strings. The author details the hex and decimal representations, the 4-character limitation, and practical uses for logging. While noting this technique is less relevant in Swift, the article provides a historical perspective on a clever C programming pattern in Apple's frameworks.

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#Io #Enum #Objective C