How can I detect when a UITableView has scrolled all the way down / up?

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I've got a view that has 3 tableView's. One is the "Main Table View", and then I have an 'Answers Table View' and 'Percentage Table View'.

When the screens loads, the Main Table View occupies the top 95% of the screen. The bottom of the screen is a UIView containing 2 buttons. "Answers" and "Percentage".

The way it works, is if I click "Percentage" it changes the height of the Main Table View to 0, and gives that height to the Answers Table View. This animates the "Answers/Percentage" View to the top, and reveals either the Answers or Percentage TableView below it.

Here's an example:

As you can see, I click on "Percentage" which animates it up. If you click on "Percentage" again it animates it back down.

However, what I want to do is if the "Answers/Percentage" view is at the bottom of the View, and the user scrolls the Main Feed UP reaches the very end of the tableView's contents (not just the end, but the end and a little bit more), I want to animate it up like in the .gif.

Similarly, if the "Answers/Percentage" is at the top, and the user scrolls the lower "Answers Table View" down past a certain point where there is no more data above, it will completely animate.

Also, I do not ever want the "Answers/Percentage" view to be in the middle, and showing a tableview both top and bottom. All one, or the other, but not a bit of both. Which I have right now.

What I need to know is... how can I detect if the user has scrolled past the very top or very bottom of the table view +30 pixels for example, to initiate my animation?


You can use the contentOffset property of the table view.

if(tableView.contentOffset.y >= (tableView.contentSize.height - tableView.frame.size.height)) {
    // Start the animation
}

I haven't tested this, but let me know if it works.