I have observed behavior of app in iOS 10.2.1 device and iOS 10.3 beta 3 device for https://developer.apple.com/library/content/samplecode/GenericKeychain/Introduction/Intro.html
Keychain data is being deleted in iOS 10.3 beta 3. That was still found in earlier versions.
Do we have any alternative to do this?
Now that 10.3 has been officially released, it's been confirmed by several parties, including in this Apple's developers forum post, that this issue is not present in the final release.
Keychain data is not being deleted upon app's uninstall.