Swift:下拉以解除`UITableViewController`

Question

我想拉下来解雇UITableViewController所以我用了scrollViewDidScroll方法,但它不起作用!

    class CommentViewController: PFQueryTableViewController {

        private let tableHeaderHeight: CGFloat = 350.0



extension CommentViewController
{
    override func scrollViewDidScroll(scrollView: UIScrollView)
    {



            // Pull down to dismiss TVC 
            let offsetY = scrollView.contentOffset.y
            let adjustment: CGFloat = 130.0

            // for later use
            if (-offsetY) > (tableHeaderHeight+adjustment) {
                self.dismissViewControllerAnimated(true, completion: nil)
                }
 }
    }

Answer 1

您必须实现额外的平移手势识别器,它将同时识别scrollView的平移手势识别器.然后,当表格视图已滚动到顶部时,您可以确定用户是否正在用手指平移.例如

var isTrackingPanLocation = false
var panGestureRecognizer: UIPanGestureRecognizer!

public override func viewDidLoad() {
    super.viewDidLoad()
    tableView.bounces = false
    panGestureRecognizer = UIPanGestureRecognizer(target: self, 
                                                  action: #selector(panRecognized(gestureRecognizer:)))
    panGestureRecognizer.delegate = self
    tableView.addGestureRecognizer(panGestureRecognizer)
}

public func panRecognized(recognizer: UIPanGestureRecognizer) {
    if recognizer.state == .began && tableView.contentOffset.y == 0 {
        recognizer.setTranslation(CGPoint.zero, inView : tableView)

        isTrackingPanLocation = true
    } else if recognizer.state != .ended && 
              recognizer.state != .cancelled && 
              recognizer.state != .failed && 
              isTrackingPanLocation {
        let panOffset = recognizer.translationInView(tableView)

        // determine offset of the pan from the start here. 
        // When offset is far enough from table view top edge - 
        // dismiss your view controller. Additionally you can 
        // determine if pan goes in the wrong direction and 
        // then reset flag isTrackingPanLocation to false

        let eligiblePanOffset = panOffset.y > 200
        if eligiblePanOffset {
            recognizer.enabled = false
            recognizer.enabled = true
            dismissViewControllerAnimated(true, completion: nil)
        }

        if panOffset.y < 0 {
            isTrackingPanLocation = false
        }
    } else {
        isTrackingPanLocation = false
    }
}

public func gestureRecognizer(gestureRecognizer: UIGestureRecognizer, 
    shouldRecognizeSimultaneouslyWithGestureRecognizer 
                    otherGestureRecognizer: UIGestureRecognizer) -> Bool {
    return true
}

Answer 2

斯威夫特4

var panGestureRecognizer : UIPanGestureRecognizer!

override func viewDidLoad() {
    mainTableView.bounces = true
    panGestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(self.panRecognized))
    panGestureRecognizer.delegate = self
    mainTableView.addGestureRecognizer(panGestureRecognizer)
}


@objc func panRecognized(recognizer: UIPanGestureRecognizer) {
    if recognizer.state == .began && mainTableView.contentOffset.y == 0 {

    } else if recognizer.state != .ended && recognizer.state != .cancelled && recognizer.state != .failed {
        let panOffset = recognizer.translation(in: mainTableView)
        let eligiblePanOffset = panOffset.y > 300
        if eligiblePanOffset {
            recognizer.isEnabled = false
            recognizer.isEnabled = true
            self.dismiss(animated: true, completion: nil)
        }
    }
}


func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
    return true
}