Animate uibutton on table swipe?

Question

iOS

Guys, how to implement a smooth animation of the uibutton, which is located on top of the table, so that when scrolling down the table, the button disappears smoothly, up appears, as in Vkontakte in the news feed, the button at the bottom of the blue "records". If through scrollviewdidscroll just pointing to hidden, then the button disappears abruptly, but it should be beautiful, smooth

Answer 1

Change not hidden, but the alpha property, depending on the scrollOffset scroll view in this very method