Saving Sensitive Information to iOS Keychain

secure.swift

func testPaswordRetrive() {
    let  password = "123456"
    let account = "User"
    keyChainService.save(password, for: account)
    XCTAssertEqual(keyChainService.retrivePassword(for: account), password)
}
//...
class KeychainService {
  
    func save(_ password: String, for account: String) {
        let password = password.data(using: String.Encoding.utf8)!
        let query: [String: Any] = [kSecClass as String: kSecClassGenericPassword,
                                    kSecAttrAccount as String: account,
                                    kSecValueData as String: password]
        let status = SecItemAdd(query as CFDictionary, nil)
        guard status == errSecSuccess else { return print("save error")
    }
      
    func retrivePassword(for account: String) -> String? {
        let query: [String: Any] = [kSecClass as String: kSecClassGenericPassword,
                                kSecAttrAccount as String: account,
                                kSecMatchLimit as String: kSecMatchLimitOne,
                                kSecReturnData as String: kCFBooleanTrue]
    
    
        var retrivedData: AnyObject? = nil
        let _ = SecItemCopyMatching(query as CFDictionary, &retrivedData)
    
    
        guard let data = retrivedData as? Data else {return nil}
        return String(data: data, encoding: String.Encoding.utf8)
    }  
}

Optionally, save a hashed version of your sensitive information using CryptoSwift

func saveEncryptedPassword(_ password: String, for account: String) {
    let salt = Array("salty".utf8)
    let key = try! HKDF(password: Array(password.utf8), salt: salt, variant: .sha256).calculate().toHexString()
    keychainService.save(key, for: account)
}