所有你需要的是一种方式在用户首次注册应用时验证用户是家长，学生还是教师。之后，您在Firebase数据库的用户信息部分（type = Parent，student或teacher）中添加了type变量。然后，当他们登录时，您将检索他们的类型。并显示正确的相应界面。

All you need is a way to verify that the user is a Parent, Student, or Teacher when they first sign up for the app. After that you put a 'type' variable in their user info section of the Firebase Database (type = Parent, student or teacher). Then when they login, you retrieve their 'type'. And show the correct corresponding interface.