… using an open URL command, on url made by string "prefs:root=WIFI". I've tested and it worked with me.
This is not a supported technique (and the last time I checked the iOS sandbox correctly blocks it). You can read this post for more advice on this front.
But I wondering if it's possible to open Settings Pannel as view (or a subview) inside my app.
No.
If you'd like to see support for stuff like this added in the future, I encourage you to file an enhancement request describing your requirements. While we may have seen similar requests many times before, a fresh bug report will allow you to express your needs in your own terms, and allow iOS engineering to gauge the level of demand.
Please post your bug number, just for the record.
Share and Enjoy
—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware
let myEmail = "eskimo" + "1" + "@apple.com"