保存到app default

a.swift

private let defaults = UserDefaults.standard
private let usernameKey = "username"
private let passwordKey = "password"

func saveLoginInfo(username: String, password: String) {
    defaults.set(username, forKey: usernameKey)
    defaults.set(password, forKey: passwordKey)
}

func getSavedUsername() -> String {
    return defaults.string(forKey: usernameKey) ?? ""
}

func getSavedPassword() -> String {
    return defaults.string(forKey: passwordKey) ?? ""
}