LogKit

Structured, filterable logging for iOS and macOS — built in pure Swift.

---

What is LogKit?

LogKit replaces scattered print() calls with a structured logging system. Every log has a level, category, file, function, line number, and timestamp — so you always know where a message came from and why.

// Instead of this
print("User logged in")

// Use this
Log.info("User logged in")
// 💬 [14:32:01.245] [INFO] [App] HomeViewModel.swift:42 → User logged in

---

Installation

In Xcode go to File → Add Package Dependencies and paste:

https://github.com/codewithswiftly/LogKit.git

Or in Package.swift:

.package(url: "https://github.com/codewithswiftly/LogKit.git", from: "1.0.0")

---

Quick Start

Global logger (simplest)

import LogKit

Log.verbose("Entering fetchUser()")
Log.debug("Cache hit for user ID 42")
Log.info("User logged in successfully")
Log.warning("Token expiring in 5 minutes")
Log.error("Network request failed: \(error.localizedDescription)")

Per-feature logger (recommended)

// Create one logger per feature/module
let networkLogger  = Logger(category: "Networking").addDestination(ConsoleDestination())
let authLogger     = Logger(category: "Auth").addDestination(ConsoleDestination())
let paymentLogger  = Logger(category: "Payments").addDestination(ConsoleDestination())

networkLogger.info("Request started: GET /users")
authLogger.warning("Invalid token, refreshing...")
paymentLogger.error("Payment declined: \(error)")

---

Log Levels

Level	Emoji	Use for
.verbose	💬	Fine-grained flow, function entry/exit
.debug	🔧	Values, state during development
.info	ℹ️	General app events and milestones
.warning	⚠️	Unexpected but recoverable situations
.error	❌	Failures that need attention

---

Destinations

Destinations control where logs go. Add as many as you need to a single logger.

ConsoleDestination

Prints to the Xcode debug console.

let logger = Logger(category: "App")
    .addDestination(ConsoleDestination(minimumLevel: .debug))

FileDestination

Writes logs to a file on disk — great for crash reporting or QA builds.

let logFile = FileManager.default
    .urls(for: .documentDirectory, in: .userDomainMask)[0]
    .appendingPathComponent("app.log")

let logger = Logger(category: "App")
    .addDestination(FileDestination(fileURL: logFile, minimumLevel: .warning))

// Read or clear the log file
let destination = FileDestination(fileURL: logFile)
print(destination.readLogs())
destination.clearLogs()

MemoryDestination

Stores logs in memory — useful for showing an in-app log viewer or in tests.

let memory = MemoryDestination(maxEntries: 200)
let logger = Logger(category: "App").addDestination(memory)

// Access stored entries
let allLogs     = memory.entries
let onlyErrors  = memory.entries(for: .error)
let networkLogs = memory.entries(for: "Networking")
memory.clear()

Multiple Destinations

let logger = Logger(category: "App")
    .addDestination(ConsoleDestination(minimumLevel: .debug))    // All logs to console
    .addDestination(FileDestination(fileURL: logFile, minimumLevel: .warning))  // Only warnings+ to file

---

Filtering Logs

Use LogFilter to search and filter entries stored in MemoryDestination.

let entries = memory.entries

// By exact level
let errors = LogFilter.filter(entries, by: .level(.error))

// By minimum level (warning and above)
let serious = LogFilter.filter(entries, by: .minimumLevel(.warning))

// By category
let networkLogs = LogFilter.filter(entries, by: .category("Networking"))

// By keyword search
let timeouts = LogFilter.filter(entries, by: .keyword("timeout"))

// By date range
let recent = LogFilter.filter(entries, by: .dateRange(from: oneHourAgo, to: now))

// Multiple criteria combined (AND logic)
let networkErrors = LogFilter.filter(entries, by: .level(.error), .category("Networking"))

---

Disabling Logging

// Disable a specific logger
logger.isEnabled = false

// Or set a higher minimum level to reduce noise in production
let console = ConsoleDestination(minimumLevel: .warning)

---

Real World Example — Networking Layer

class NetworkManager {

    private let logger = Logger(category: "Networking")
        .addDestination(ConsoleDestination())

    func fetchUser(id: Int) async throws -> User {
        logger.info("Fetching user \(id)")

        do {
            let user: User = try await client.request(UserAPI.profile(id: id))
            logger.debug("Received user: \(user.name)")
            return user
        } catch {
            logger.error("Failed to fetch user \(id): \(error.localizedDescription)")
            throw error
        }
    }
}

---

Project Structure

LogKit/
├── Sources/LogKit/
│   ├── LogLevel.swift         # Levels: verbose, debug, info, warning, error
│   ├── LogEntry.swift         # Data model for a single log line
│   ├── LogDestination.swift   # Protocol + Console, File, Memory destinations
│   ├── Logger.swift           # Logger class + Log global shorthand
│   └── LogFilter.swift        # Filter entries by level, category, keyword
└── Tests/LogKitTests/
    └── LogKitTests.swift

---

Requirements

• iOS 15+ / macOS 12+
• Swift 5.9+
• Xcode 15+
• Zero dependencies

---

License

MIT © 2026 Rahul Das Gupta

---

Show Your Support

If you found this project useful, consider giving it a ⭐️ on GitHub!