objective-c - iOS 中时如何判断保存的密码是否过期

Question

账户和密码是用keychain保存，假设需求 是三十天未登录 让其重新输入账户名和密码 不是直接登录

Answer 1

Use NSUserDefault to save a timestamp
Then every time you open the APP, just judge the time difference between the current timestamp and the saved timestamp

Answer 2

nsdate gets the current date, and then subtracts it from the cached nsdate of the current day