如何在 Swift 中将 UILongPressGestureRecognizer 与 UICollectionViewCell 一起使用？

Question

I would like to figure out how to println the indexPath of a UICollectionViewCell when I long press on a cell.

How can I do that in Swift?

I have looked all over for an example of how to do this; can't find one in Swift.

Answer 1

First you your view controller need to be UIGestureRecognizerDelegate . Then add a UILongPressGestureRecognizer to your collectionView in your viewcontroller's viewDidLoad() method

class ViewController: UIViewController, UIGestureRecognizerDelegate {

     override func viewDidLoad() {
         super.viewDidLoad()

        let lpgr = UILongPressGestureRecognizer(target: self, action: "handleLongPress:")
         lpgr.minimumPressDuration = 0.5
         lpgr.delaysTouchesBegan = true
         lpgr.delegate = self
         self.collectionView.addGestureRecognizer(lpgr)
    }

The method to handle long press:

func handleLongPress(gestureReconizer: UILongPressGestureRecognizer) {
        if gestureReconizer.state != UIGestureRecognizerState.Ended {
            return
        }

        let p = gestureReconizer.locationInView(self.collectionView)
        let indexPath = self.collectionView.indexPathForItemAtPoint(p)

        if let index = indexPath {
            var cell = self.collectionView.cellForItemAtIndexPath(index)
            // do stuff with your cell, for example print the indexPath
             println(index.row)
        } else {
            println("Could not find index path")
        }
    }

This code is based on the Objective-C version of this answer .

Answer 2

ztan answer's converted to swift 3 syntax and minor spelling update:

func handleLongPress(_ gestureRecognizer: UILongPressGestureRecognizer) {
    if gestureRecognizer.state != UIGestureRecognizerState.ended {
      return
    }

    let p = gestureRecognizer.location(in: collectionView)
    let indexPath = collectionView.indexPathForItem(at: p)

    if let index = indexPath {
      var cell = collectionView.cellForItem(at: index)
      // do stuff with your cell, for example print the indexPath
      print(index.row)
    } else {
      print("Could not find index path")
    }
}

Answer 3

One thing I found was that:

if gestureReconizer.state != UIGestureRecognizerState.Ended {
    return
}

doesn't place pin until you release the longpress, which is OK, but I found

if gestureRecognizer.state == UIGestureRecognizerState.Began { }  

around the whole function will prevent multiple pin placements while letting the pin appear as soon as the timer delay is satisfied.

Also, one typo above: Reconizer -> Recognizer

Answer 4

The method handleLongProgress converted to swift 3 syntax works fine. I just want to add that the initialization of lpgr should be changed to:

let lpgr = UILongPressGestureRecognizer(target: self, action: #selector(handleLongPress(gestureReconizer:)))

Answer 5

Swift 5 & Swift 4 Table View Cell

override func viewDidLoad() {
    //MARK:- Add Long Gesture
    let longPressGesture = UILongPressGestureRecognizer(target: self, action: #selector(longPressed))
    longPressGesture.minimumPressDuration = 1.0 // 1 second press
    longPressGesture.allowableMovement = 15 // 15 points
    longPressGesture.delegate = self
    self.tablev.addGestureRecognizer(longPressGesture)
}


//MARK:- Long Press Gesture
@objc func longPressed(sender: UILongPressGestureRecognizer)
{

    if sender.state == UIGestureRecognizer.State.ended {
        return
    }
    else if sender.state == UIGestureRecognizer.State.began
    {
        let p = sender.location(in: self.tablev)
        let indexPath = self.tablev.indexPathForRow(at: p)

        if let index = indexPath {
            var cell = self.tablev.cellForRow(at: index)
            // do stuff with your cell, for example print the indexPath
            print(index.row)
            print("longpressed Tag: \(index.row)")
        } else {
            print("Could not find index path")
        }
    }
}

Answer 6

ztan answer's converted to swift 4 syntax and minor spelling update:

@objc func handleLongPress(_ gestureRecognizer: UILongPressGestureRecognizer) {
    guard gestureRecognizer.state != .ended else { return }

    let point = gestureRecognizer.location(in: collectionView)

    if let indexPath = collectionView.indexPathForItem(at: point), 
       let cell = collectionView.cellForItem(at: indexPath) {
        // do stuff with your cell, for example print the indexPath
        print(indexPath.row)
    } else {
        print("Could not find index path")
    }
}

Answer 7

if objc func calling causes an error ( Swift 5 ),

Replace Selector("handleLongPress") with #selector(self. handleLongPress) here is the full implementation.

in your viewDidLoad(),

        let lpgr = UILongPressGestureRecognizer(target: self, 
                             action:#selector(self.handleLongPress))
        lpgr.minimumPressDuration = 1
        lpgr.delaysTouchesBegan = true
        lpgr.delegate = self
        self._mapView.addGestureRecognizer(lpgr)

and implement this in your viewcontroller,

@objc func handleLongPress(gestureRecognizer: UILongPressGestureRecognizer) {
        if gestureReconizer.state != UIGestureRecognizerState.Ended {
        return
    }

    let p = gestureReconizer.locationInView(self.collectionView)
    let indexPath = self.collectionView.indexPathForItemAtPoint(p)

    if let index = indexPath {
        var cell = self.collectionView.cellForItemAtIndexPath(index)
        // do stuff with your cell, for example print the indexPath
         println(index.row)
    } else {
        println("Could not find index path")
    }

 }