Get value from Result.Error in swift

[ysavr]

ContentView.swift:

func login(username: String, password: String) {
if let result = loginRepository.login(username: username, password: password) as? ResultSuccess {
print("Successful login. Welcome, (result.data.displayName)")
} else {
print("Error while logging in")
}
}

login DataSource:

class LoginDataSource {
fun login(username: String, password: String): Result<LoggedInUser> { try { // TODO: handle loggedInUser authentication val fakeUser = LoggedInUser(randomUUID(), "Jane Doe") return Result.Success(fakeUser) } catch (e: Throwable) { return Result.Error(RuntimeException("Error logging in", e)) } }
fun logout() { // TODO: revoke authentication }}

how to get RuntimeException message if Result not success from ContentView.swift?