Why is the scroll view being nil? - swift

Question

I have the following code:
extension SegmentedControlViewController: UIScrollViewDelegate {
func scrollViewDidScroll(_ scrollView: UIScrollView) {
// this checks for whether contentOffset.x is around 10 (contented shifted to the right by 10 points)
if abs(scrollView.contentOffset.x - 10) < 1 {
print("works")
}
}
}
#IBOutlet weak var scrollView: UIScrollView!
then I call the function in the viewDidLoad like this:
scrollViewDidScroll(scrollView)
Although I am always getting the error message
Thread 1: Fatal error: Unexpectedly found nil while implicitly unwrapping an Optional value
What am I doing wrong, how to Get the scroll view to not be nil.

Answer 1

Assign the scroll view's .delegate in viewDidLoad() and start scrolling:
class SegmentedControlViewController: UIViewController {
#IBOutlet weak var scrollView: UIScrollView!
override func viewDidLoad() {
super.viewDidLoad()
// assign the delegate
scrollView.delegate = self
}
}
extension SegmentedControlViewController: UIScrollViewDelegate {
func scrollViewDidScroll(_ scrollView: UIScrollView) {
// this checks for whether contentOffset.x is around 10 (contented shifted to the right by 10 points)
if abs(scrollView.contentOffset.x - 10) < 1 {
print("works")
}
}
}
Edit
If you want to check if the scroll view content has been dragged to the right more than 10 points, use this:
extension SegmentedControlViewController: UIScrollViewDelegate {
func scrollViewDidScroll(_ scrollView: UIScrollView) {
// this checks for whether contentOffset.x is around 10 (contented shifted to the right by 10 points)
if scrollView.contentOffset.x < 10 {
print("scroll content has been dragged to the right more than 10 points")
}
}
}