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

Converted @bandejapaisa answer to Swift 5:

Properties used by UIScrollViewDelegate:

var lastOffset: CGPoint = .zero
var lastOffsetCapture: TimeInterval = .zero
var isScrollingFast: Bool = false

And the scrollViewDidScroll function:

func scrollViewDidScroll(scrollView: UIScrollView) {

    let currentOffset = scrollView.contentOffset
    let currentTime = Date.timeIntervalSinceReferenceDate
    let timeDiff = currentTime - lastOffsetCapture
    let captureInterval = 0.1
    
    if timeDiff > captureInterval {
        
        let distance = currentOffset.y - lastOffset.y     // calc distance
        let scrollSpeedNotAbs = (distance * 10) / 1000     // pixels per ms*10
        let scrollSpeed = fabsf(Float(scrollSpeedNotAbs))  // absolute value
        
        if scrollSpeed > 0.5 {
            isScrollingFast = true
            print("Fast")
        } else {
            isScrollingFast = false
            print("Slow")
        }
        
        lastOffset = currentOffset
        lastOffsetCapture = currentTime
        
    }
}