Easy Keychain use with Swift 4

Keychain.swift

//
//  Keychain.swift
//  SecKeychain
//
//  Created by Paul Wagener on 01-11-17.
//  Copyright © 2017 Paul Wagener. All rights reserved.
//

import Foundation

import Security

public class Keychain
{
    public class func set(key: String, value: String) -> Bool
    {
        if let data = value.data(using: String.Encoding.utf8)
        {
            return set(key: key, value: data)
        }
        
        return false
    }
    
    public class func set(key: String, value: Data) -> Bool
    {
        let query = [
            kSecClass       : kSecClassGenericPassword,
            kSecAttrAccount : key,
            kSecValueData   : value
        ] as CFDictionary
        
        SecItemDelete(query)
        
        return SecItemAdd(query, nil) == noErr
    }
    
    public class func get(key: String) -> String?
    {
        if let data = getData(key: key)
        {
            return String(data: data as Data, encoding: String.Encoding.utf8)
        }
        
        return nil
    }
    
    public class func getData(key: String) -> Data?
    {
        let query = [
            kSecClass       : kSecClassGenericPassword,
            kSecAttrAccount : key,
            kSecReturnData  : kCFBooleanTrue,
            kSecMatchLimit  : kSecMatchLimitOne
        ] as CFDictionary
        
        var dataTypeRef: AnyObject?
        let status = SecItemCopyMatching(query, &dataTypeRef)
        
        if status == noErr && dataTypeRef != nil
        {
            return dataTypeRef as? Data
        }
        
        return nil
    }
    
    public class func delete(key: String) -> Bool
    {
        let query = [
            kSecClass       : kSecClassGenericPassword,
            kSecAttrAccount : key
        ] as CFDictionary
        
        return SecItemDelete(query) == noErr
    }
    
    public class func clear() -> Bool
    {
        let query = [
            kSecClass: kSecClassGenericPassword
        ] as CFDictionary
        
        return SecItemDelete(query) == noErr
    }
}