Assign function to UIScrollView when scrolling (Swift)

Question

I have a UIViewController with a UIScrollView I've added in Interface Builder. I want to have scrollView functions so I can detect if it's been scrolled up or down. My scroll view is attached with an IBOutlet called "mainScroll." Here is my code:

var lastContentOffset: CGFloat = 0
@IBOutlet weak var mainScroll: UIScrollView!

func scrollViewWillBeginDragging(_ scrollView: UIScrollView) {
    self.lastContentOffset = mainScroll.contentOffset.y
}

func scrollViewDidScroll(_ scrollView: UIScrollView) {
    if (self.lastContentOffset < mainScroll.contentOffset.y) {
        // did move up
        print("Did Move Up")
    } else if (self.lastContentOffset > mainScroll.contentOffset.y) {
        // did move down
        print("Did Move Down")
    } else {
        // didn't move
    }
}

I've added UIScrollViewDelegate to my class. I have a feeling I'm not using the scrollView delegate callbacks properly. How can I take these functions and assign them to my "mainScroll"?

You need to connect the scroll view's delegate in the storyboard. — rmaddy
– rmaddy, Commented Feb 22, 2019 at 0:45

Shehata Gamal · Accepted Answer · 2019-02-22 00:40:40Z

1

May be you need this in viewDidLoad

mainScroll.delegate = self

answered Feb 22, 2019 at 0:40

Shehata Gamal

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