Swift - TableView的协议代理无法正常工作 - 以模态方式呈现

I have one view controller with a button that when clicked goes to a second view controller with a table view. The two scenes are linked through storyboard, as Present Modally. I want the text of the button in the first view controller to change when a row is selected in the table view of the second view controller.I have one view controller with a button that w