let password: String = ...
let keychainItem = KeychainPasswordItem(service: "com.dp.service.demo", account: "dpdemo", accessGroup: nil)
try keychainItem.savePassword(password)

let passwordItems = try KeychainPasswordItem.passwordItems(forService: "com.dp.service.demo", accessGroup: nil)
if let keychainItem = passwordItems.first(where: { (item) -> Bool in
		return item.account == "dpdemo"
}) {
  	let password = try deviceUUIDItem.readPassword()
}