UnionKeychain

A lightweight, type-safe Swift keychain wrapper for iOS 17+ and macOS 14+.

Features

• Simple static API for quick access to keychain storage
• Type-safe methods for strings, booleans, and binary data
• Property wrappers for declarative storage
• Persistent storage that survives app uninstalls
• Perfect for free trial tracking and authentication tokens

Installation

Swift Package Manager

Add the following dependency to your Package.swift file:

.package(url: "https://github.com/yourusername/union-keychain.git", from: "1.0.0")

Or add it directly in Xcode using File → Add Packages...

Usage

Basic Storage

import UnionKeychain

Keychain.setString("secret_token", forKey: "apiToken")
if let token = Keychain.getString(forKey: "apiToken") {
    print("Token: \(token)")
}

Keychain.setBool(true, forKey: "hasCompletedOnboarding")
if Keychain.getBool(forKey: "hasCompletedOnboarding") == true {
    showMainInterface()
}

let imageData = UIImage(named: "avatar")?.jpegData(compressionQuality: 0.8)
Keychain.setData(imageData, forKey: "profileImage")
if let data = Keychain.getData(forKey: "profileImage") {
    let image = UIImage(data: data)
}

Convenience Properties

Keychain.bearerToken = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9..."

if let token = Keychain.bearerToken {
    request.setValue("Bearer \(token)", forHTTPHeaderField: "Authorization")
}

if !Keychain.usedFreeAccount {
    Keychain.usedFreeAccount = true
    presentFreeTrial()
}

Property Wrappers

class UserSession {
    @KeychainString(key: "username")
    var username: String?
    
    @KeychainBool(key: "isPremium", defaultValue: false)
    var isPremium: Bool
    
    @KeychainData(key: "certificate")
    var certificate: Data?
}

let session = UserSession()
session.username = "john_doe"
session.isPremium = true

Persistent Free Trial Tracking

Unlike UserDefaults, keychain data persists even when the app is uninstalled and reinstalled. This makes it perfect for tracking free trial usage:

func checkTrialEligibility() {
    if Keychain.usedFreeAccount {
        showPaywall()
    } else {
        Keychain.usedFreeAccount = true
        startFreeTrial()
    }
}

Users cannot bypass trial restrictions by simply reinstalling your app.

Custom Service Names

Keychain.setString("value", forKey: "key", service: "com.myapp.custom")
let value = Keychain.getString(forKey: "key", service: "com.myapp.custom")

Removing Values

Set any value to nil to remove it from the keychain:

Keychain.setString(nil, forKey: "apiToken")
Keychain.setBool(nil, forKey: "isPremium")
Keychain.setData(nil, forKey: "certificate")

API Reference

Static Methods

• getString(forKey:service:) -> String?
• setString(_:forKey:service:) -> Bool
• getData(forKey:service:) -> Data?
• setData(_:forKey:service:) -> Bool
• getBool(forKey:service:) -> Bool?
• setBool(_:forKey:service:) -> Bool

Static Properties

• defaultService: String - The default service identifier
• bearerToken: String? - Convenience property for auth tokens
• usedFreeAccount: Bool - Convenience property for trial tracking

Property Wrappers

• @KeychainString - Optional string storage
• @KeychainBool - Boolean storage with default value
• @KeychainData - Optional binary data storage

License

MIT License