iPhone UIScrollView Speed Check

Question

I know how to get the contentOffset on movement for a UIScrollView, can someone explain to me how I can get an actual number that represents the current speed of a UIScrollV

Answer 1

Here is another smart way to do this in SWIFT :-

func scrollViewWillEndDragging(scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
    if velocity.y > 1.0 || velocity.y < -1.0 && self.sendMessageView.isFirstResponder() {
        // Somthing you want to do when scrollin fast.
        // Generally fast Vertical scrolling.
    }
}

So if you scrolling vertically you should use velocity.y and also if you are scrolling horizontally you should use velocity.x . Generally if value is more than 1 and less than -1, it represent generally fast scrolling. So you can change the speed as you want. +value means scrolling up and -value means scrolling down.

Answer 2

You can see PageControl sample code about how to get the contentOffset of scrollview.

The contentOffset on movement can be obtained from UIScrollViewDelegate method, named - (void)scrollViewDidScroll:(UIScrollView *)scrollView, by querying scrollView.contentOffset. Current speed can be calculated by delta_offset and delta_time.

• Delta_offset = current_offset - pre_offset;
• Delta_time = current_time - pre_time;