Preface:Have you ever encountered a requirement where the product requires the same user to be allowed to log in at the same time according to backend Settings, or when it is not allowed to log in at the same time, it is necessary to force the previous offline scenario. This article will lead you to implement a simple requirement for this scenario...

The first time I encountered this kind of thing, it was too scaryRecently, Ms. Xie (pseudonym), a resident from another city, shared her almost deceived experience on social media: her Apple ID (note: Apple account) was modified 13 times by strangers in the early morning...