使用平移手势选择多个表格视图单元格
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【中文标题】使用平移手势选择多个表格视图单元格【英文标题】：Using a pan gesture to select multiple tableview cells 【发布时间】：2018-12-05 08:45:09 【问题描述】：我正在尝试在表格视图上实现平移手势，以便在平移时选择多个单元格
我遇到的问题是当用户平移表格中的最后一个可见单元格时让 tableview 滚动到下一个单元格，或者当用户平移第一个可见单元格时滚动到上一个单元格
目前，当我的平移到达表中最后一个可见或第一个可见行时，它会为下一行设置动画，但仅针对前 2 或 3 行，然后停止滚动
经过一番挖掘，似乎是因为 panGesture 没有被调用，因为用户的手指在桌子边缘是静止的。
一旦平底锅到达桌子的顶部或底部边缘，我将如何保持表格滚动？
这是我当前的代码：
import UIKit
class MyView: UIViewController, UITableViewDelegate, UITableViewDataSource, UIGestureRecognizerDelegate
var lastSelectedCell = IndexPath()
var gesturePan: UIPanGestureRecognizer!
var totalRows = 100
@IBOutlet weak var tableView: UITableView!
override func viewDidLoad()
super.viewDidLoad()
//setup table gestures
addGesturesToTable()
extension MyView
//MARK: - Tableview code
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int
return totalRows
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
let lab = cell.viewWithTag(1) as! UILabel
lab.text = "\(indexPath.row)"
return cell
extension MyView
//MARK: - Gesture code
func addGesturesToTable()
tableView.canCancelContentTouches = false
tableView.allowsMultipleSelection = true
//add long press gesture to initiate pan
let gestureLongPress = UILongPressGestureRecognizer(target: self, action: #selector(enablePan))
gestureLongPress.minimumPressDuration = 0.25
gestureLongPress.delaysTouchesBegan = true
gestureLongPress.delegate = self
tableView.addGestureRecognizer(gestureLongPress)
//add pan gesture to select cells on drag
gesturePan = UIPanGestureRecognizer(target: self, action: #selector(userPanned(_:)))
gesturePan.isEnabled = false
gesturePan.delegate = self
tableView.addGestureRecognizer(gesturePan)
//LongPress gesture(to enable pan)
@objc func enablePan()
gesturePan.isEnabled = true
//Pan gesture
@objc func userPanned(_ panGesture: UIPanGestureRecognizer)
//if starting to pan
if panGesture.state == .began
tableView?.isUserInteractionEnabled = false
tableView?.isScrollEnabled = false
//if pan position is changed
else if panGesture.state == .changed
//get indexPath at pan location
let location: CGPoint = panGesture.location(in: tableView)
if let indexPath: IndexPath = tableView?.indexPathForRow(at: location)
//if the index path.row is the first or last row of the data set
if(indexPath.row >= totalRows - 1 || indexPath.row <= 0)
print("data start/end reached")
//otherwise
else
//get pan direction
var direction: String!
let velocity = panGesture.velocity(in: tableView)
if(velocity.y > 0)
direction = "Down"
else
direction = "Up"
//if it's a new cell
if indexPath != lastSelectedCell
//select/deselect it
self.selectPannedCell(indexPath, selected: true, location: location, panDirection: direction)
//update last selected cell
lastSelectedCell = indexPath
//if pan gesture is ending
else if panGesture.state == .ended
//re-enable tableview interaction
tableView.isScrollEnabled = true
tableView.isUserInteractionEnabled = true
//disable pan gesture
panGesture.isEnabled = false
//select/deselect the panned over cell
func selectPannedCell(_ indexPath: IndexPath, selected: Bool, location: CGPoint, panDirection: String)
if let cell = tableView.cellForRow(at: indexPath)
//if cell is already selected
if cell.isSelected
//deselect row
tableView.deselectRow(at: indexPath, animated: true)
//if panning down
if(panDirection == "Down")
//if it's the last cell
if(indexPath >= tableView.indexPathsForVisibleRows![(tableView.indexPathsForVisibleRows?.count)!-1])
//scroll to the next cell after the last visible
let scrollToIndex = IndexPath(row: indexPath.row + 1, section:0)
tableView.scrollToRow(at: scrollToIndex, at:
UITableViewScrollPosition.bottom, animated: true)
//if panning up
else
//if it's the first cell
if(indexPath <= tableView.indexPathsForVisibleRows![0])
//scroll to the previous cell before first visible
let firstIndex = IndexPath(row: indexPath.row - 1, section:0)
tableView.scrollToRow(at: firstIndex, at:
UITableViewScrollPosition.top, animated: true)
else
//select row
tableView.selectRow(at: indexPath, animated: true, scrollPosition: UITableViewScrollPosition.none)
//if panning down
if(panDirection == "Down")
//if it's the last cell
if(indexPath >= tableView.indexPathsForVisibleRows![(tableView.indexPathsForVisibleRows?.count)!-1])
//scroll to the next cell after the last visible
let lastIndex = IndexPath(row: indexPath.row + 1, section:0)
tableView.scrollToRow(at: lastIndex, at:
UITableViewScrollPosition.bottom, animated: true)
else
//if it's the first cell
if(indexPath <= tableView.indexPathsForVisibleRows![0])
//scroll to the previous cell before first visible
let firstIndex = IndexPath(row: indexPath.row - 1, section:0)
tableView.scrollToRow(at: firstIndex, at:
UITableViewScrollPosition.top, animated: true)
提前致谢
【问题讨论】：
【参考方案1】：快速示例如何在您的情况下实现它，我认为您可以轻松地满足您的需求。
var continueScrollToBottom: Bool = false
var continueScrollToTop: Bool = false
@objc func updatePanGesture(_ sender: UIPanGestureRecognizer)
switch sender.state
case .changed:
continueScrollToBottom = false
continueScrollToTop = false
// If you reach to the top make scroll constant
// You can define there another condition which more suitable for you
if sender.location(in: self.view).y < 200
continueScrollToTop = true
continueScrollToBottom = false
self.startScrollToTop()
return
// If you reach to the bottom make scroll constant
// You can define there another condition which more suitable for you
if sender.location(in: self.view).y > 350
continueScrollToBottom = true
continueScrollToTop = false
self.startScrollToBottom()
return
case .ended:
continueScrollToBottom = false
continueScrollToTop = false
case .cancelled:
continueScrollToBottom = false
continueScrollToTop = false
default:
break
func startScrollToBottom()
if continueScrollToBottom
if let last = tableView.indexPathsForVisibleRows?.last, last.row+1 < countOfRows
let showNext = IndexPath(row: last.row+1, section: last.section)
tableView.scrollToRow(at: showNext, at: .bottom, animated: true)
DispatchQueue.main.asyncAfter(deadline: .now()+0.3)
self.startScrollToBottom()
func startScrollToTop()
if continueScrollToTop
if let first = tableView.indexPathsForVisibleRows?.first, first.row-1 > 0
let showNext = IndexPath(row: first.row-1, section: first.section)
tableView.scrollToRow(at: showNext, at: .top, animated: true)
DispatchQueue.main.asyncAfter(deadline: .now()+0.3)
self.startScrollToTop()
【讨论】：
感谢Gkolunia的回答，我用类似的方案解决了，但是用了一个定时器来触发连续滚动以上是关于使用平移手势选择多个表格视图单元格的主要内容，如果未能解决你的问题，请参考以下文章