Logging

Structured OSLog wrapper for Apple platforms.

print() is invisible in production, unfiltered, and always evaluates its arguments. swift-logging replaces it with Apple's unified logging system: debug messages are compiled out in release builds, every log line is filterable by category in Console.app, and sensitive values are automatically redacted.

Requirements

Platform	Minimum version
iOS	16
macOS	13
watchOS	9
tvOS	16
visionOS	1

Swift 6 · Swift Package Manager

Installation

Xcode

File → Add Package Dependencies…, paste the repository URL, then add Logging to your app target.

Package.swift

dependencies: [
    .package(url: "https://github.com/inesbcode/swift-logging.git", from: "1.0.0"),
],
targets: [
    .target(
        name: "MyApp",
        dependencies: [
            .product(name: "Logging", package: "swift-logging"),
        ]
    ),
]

Usage

Setup

Create one Logging instance per target, passing your subsystem, then store or pass it where needed:

// AppDelegate, @main struct, or dependency container
let log = Logging(subsystem: "com.mycompany.MyApp")

For quick prototyping the default init uses "com.inesb.swift-logging" as the subsystem:

let log = Logging()

Basic logging

import Logging

let log = Logging(subsystem: "com.mycompany.MyApp")

log.network.info("Request started: \(url, privacy: .public)")
log.auth.debug("Login attempt: \(email, privacy: .private)")
log.data.error("Save failed: \(error)")
log.lifecycle.notice("App moved to background")

Privacy annotations

OSLog redacts interpolated values in release builds by default. Annotate values explicitly to control what is visible in production logs:

log.auth.info("User: \(name, privacy: .private)")            // redacted in release
log.network.info("Status: \(code, privacy: .public)")        // always visible
log.auth.debug("Token: \(token, privacy: .sensitive)")       // always redacted
log.auth.info("ID: \(id, privacy: .private(mask: .hash))")  // hashed for correlation

Log levels

Level	When to use	Persisted
.debug	Verbose dev-only info (compiled out)	No
.info	General flow information	No
.notice	Important milestones	Yes
.warning	Recoverable unexpected conditions	Yes
.error	Errors that affect functionality	Yes
.fault	Critical failures (highlighted red)	Yes

Categories

Property	Intended use
.general	Events that don't fit another category
.network	Requests, responses, connectivity
.api	Endpoint calls, serialisation
.auth	Login, logout, session management
.user	Profile, preferences, account events
.data	Persistence, migrations
.cache	In-memory and on-disk cache operations
.ui	View rendering, user interactions
.navigation	Push/pop, sheets, deep links
.performance	Measurements, profiling markers
.lifecycle	App and scene lifecycle events

Viewing logs

Console.app — open Console.app, select your device or simulator, then filter by subsystem:

subsystem:com.mycompany.MyApp

Add a category to narrow results further:

subsystem:com.mycompany.MyApp category:Network

Terminal

log stream --predicate 'subsystem == "com.mycompany.MyApp"' --level debug
log stream --predicate 'subsystem == "com.mycompany.MyApp" AND category == "Network"'

License

MIT — see LICENSE.