knotchy/Sources/Knotchy/Keychain.swift

import Foundation
import Security

enum Keychain {
    private static let service = "aculix.knotchy.app"

    static func read(_ account: String) -> String? {
        let query: [String: Any] = [
            kSecClass as String: kSecClassGenericPassword,
            kSecAttrService as String: service,
            kSecAttrAccount as String: account,
            kSecReturnData as String: true,
            kSecMatchLimit as String: kSecMatchLimitOne,
        ]
        var result: AnyObject?
        guard SecItemCopyMatching(query as CFDictionary, &result) == errSecSuccess, let data = result as? Data else { return nil }
        return String(data: data, encoding: .utf8)
    }

    static func write(_ value: String, for account: String) {
        let query: [String: Any] = [
            kSecClass as String: kSecClassGenericPassword,
            kSecAttrService as String: service,
            kSecAttrAccount as String: account,
        ]
        guard !value.isEmpty else {
            SecItemDelete(query as CFDictionary)
            return
        }
        let data = Data(value.utf8)
        if SecItemUpdate(query as CFDictionary, [kSecValueData as String: data] as CFDictionary) == errSecItemNotFound {
            var item = query
            item[kSecValueData as String] = data
            item[kSecAttrAccessible as String] = kSecAttrAccessibleWhenUnlocked
            SecItemAdd(item as CFDictionary, nil)
        }
    }
}