Keychain struct for Locksmith using accessible option.

example.swift

SecureKeyValue.loadDataForKey("key", inAccessGroup: nil)

do {
    try SecureKeyValue.updateData(object, forKey: "key")
} catch {
  print("ERROR: Keychain error: \(error)")
}

do {
  try SecureKeyValue.deleteDataForKey("key")
} catch {
    print("ERROR: Keychain delete \("key") failed, value might not exist.")
}

SecureKeyValue.swift

//
//  SecureKeyValue.swift
//
//  Created by Andrew Crookston <andrew@caoos.com> on 1/5/16.
//  Copyright © 2016. License: MIT.
//

import Foundation
import Locksmith


// This is a modified version of the Locksmith struct.

struct SecureKeyValue {
    private static let KeychainObjectKey = "object"

    static func loadDataForKey(key: String) -> AnyObject? {
        return loadDataForKey(key, inAccessGroup: nil)
    }

    static func saveData(data: AnyObject, forKey key: String) throws {
        return try saveData(data, forKey: key, inAccessGroup: nil)
    }

    static func deleteDataForKey(key: String) throws {
        try deleteDataForKey(key, inAppGroup: nil)
    }


    static func loadDataForKey(key: String, inAccessGroup group: String? = nil) -> AnyObject? {
        struct ReadRequest: SecureStorable, GenericPasswordSecureStorable, ReadableSecureStorable {
            let service = LocksmithDefaultService
            let accessible = LocksmithAccessibleOption.AfterFirstUnlock
            let account: String
            let accessGroup : String?
        }
        let request = ReadRequest(account: key, accessGroup: group)
        if let data = request.readFromSecureStore()?.data {
            return data[KeychainObjectKey]
        } else {
            print("Key \(key) not found")
        }
        return nil
    }

    static func saveData(data: AnyObject, forKey key: String, inAccessGroup group: String?) throws {
        struct CreateRequest: SecureStorable, GenericPasswordSecureStorable, CreateableSecureStorable {
            let service = LocksmithDefaultService
            let accessible = LocksmithAccessibleOption.AfterFirstUnlock
            let account: String
            let data: Hash
            let accessGroup : String?
        }

        let request = CreateRequest(account: key, data: [KeychainObjectKey: data], accessGroup: group)
        return try request.createInSecureStore()
    }


    static func deleteDataForKey(key: String, inAppGroup group: String?) throws {
        struct DeleteRequest: SecureStorable, GenericPasswordSecureStorable, DeleteableSecureStorable {
            let service = LocksmithDefaultService
            let accessible = LocksmithAccessibleOption.AfterFirstUnlock
            let account: String
            let accessGroup : String?
        }

        let request = DeleteRequest(account: key, accessGroup: group)
        return try request.deleteFromSecureStore()
    }

    static func updateData(data: AnyObject, forKey key: String) throws {
        // Delete and then re-save
        do {
            try SecureKeyValue.deleteDataForKey(key)
        } catch {
            // Deletion is likely to fail if the piece of data doesn't exist yet.
            // This doesn't matter--we only tell the user about errors on the save request.
        }

        return try SecureKeyValue.saveData(data, forKey: key)
    }
}