This is an intentional change in iOS 10.3 to protect user privacy. Information that can identify a user should not be left on the device after the app that created it has been removed.
It has never been a part of the API contract that keychain items created by an app would survive when the app is removed. This has always been an implementation detail.
If a keychain item is shared with other apps, it won't be deleted until those other apps have been deleted as well.
There is documentation in the works about this change that should address questions raised in this thread.
https://forums.developer.apple.com/message/210531#210531
Does anyone know about the time of the solution? And will there be another method to replace keychain to save userData?
does anyone know about the time of the solution.
Clearly when they release 10.3.
And will there has another method to replace keychain to save userData.
Of course not. Why would they implement a feature to improve user privacy and then introduce another feature to circumvent the change?