swift - selectedTextRanges color on UITextView change to gray unexpectedly when presented UIAlertController

Question

My purpose is very simple. I would like to present UIAlertController when User selected textRange.

But, selectedTextRanges color on UITextView change to gray unexpectedly when presented UIAlertController.

This is my test App. As you can see it is very simple. There are a TextView and a UIButton.

next, I selected textrange. I modified the tint color to pink so that it would be easy to see.

and tap the button. so the UIAlertController is presented.　so far, so good :)

but, after close the UIAlertController, selectedTextRangeColor is change to gray. I don't know why :(

This symptom will occur only when on UITextView. it will not occure when on UITextField.

Does anybody know what this reason?

Finally, thank you for your thinking for this question what written in poor English.

Answer 1

等待大神解答