如何在 Swift 中将 UILongPressGestureRecognizer 与 UICollectionViewCell 一起使用？

Question

我想知道当我长按一个单元格时如何打印 UICollectionViewCell 的 indexPath。

如何在 Swift 中做到这一点？

我已经到处寻找如何做到这一点的示例；在 Swift 中找不到。

Answer 1

首先你的视图控制器需要是UIGestureRecognizerDelegate。然后在 viewcontroller 的 viewDidLoad() 方法中添加一个 UILongPressGestureRecognizer 到你的 collectionView 中

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)
    }

长按处理方法：

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")
        }
    }

此代码基于 this answer 的 Objective-C 版本。

Answer 2

ztan 答案已转换为 swift 3 语法和次要拼写更新：

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

我发现的一件事是：

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

在您松开长按之前不会放置别针，这没关系，但我发现了

if gestureRecognizer.state == UIGestureRecognizerState.Began { }  

围绕整个功能将防止多个引脚放置，同时在满足定时器延迟时让引脚出现。

另外，上面有一个错字：Reconizer -> Recognizer

Answer 4

转换为 swift 3 语法的方法 handleLongProgress 工作正常。我只是想补充一点，lpgr的初始化应该改为：

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

Answer 5

Swift 5 和 Swift 4 表格视图单元格

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 答案已转换为 swift 4 语法和次要拼写更新：

@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

如果 objc func 调用导致错误（Swift 5），

将Selector("handleLongPress") 替换为#selector(self. handleLongPress) 这是完整的实现。

在你的 viewDidLoad() 中，

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

并在您的视图控制器中实现它，

@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")
    }

 }