Twitter Login dismiss my ViewController when hitting Cancel button

[ducnv55]

I use TwitterKit to make Login function in my app. When call TWTRTwitter.sharedInstance().logIn() function (on my ViewControllerA), an AlertViewController shows up. I hit Cancel, after a while, my ViewControllerA is dismissed. AlertViewController here I searched TwitterKit's source code but found nothing that shows AlertViewController nor dismissViewController when hit Cancel. Please help me find out the reason. Thank you all.

Expected behavior

Only AlertViewController disappear

Actual behavior

After hitting Cancel button a while, my ViewController is dismissed too.

Environment

iPhone 5s iOS 10.3 Twitter app is already installed