I want to add a tap gesture to every cell in a UITableView
that edits the content in it. The two ways to add a gesture are in code or through storyboard. I tried bo
You don't need to add gesture recognizer to achieve what you are doing.
UITableViewDelegate
method tableView:didSelectRowAtIndexPath:
to detect which row is tapped (this is what exactly your tapGesture
is going to do) and then do your desired processing.tableView:didEndDisplayingCell:forRowAtIndexPath:
just before returning the cell:cell?.selectionStyle = .None
Adding gesture in awakeFromNib method seems much more easier and works fine.
class TestCell: UITableViewCell {
override func awakeFromNib() {
super.awakeFromNib()
let panGesture = UIPanGestureRecognizer(target: self,
action: #selector(gestureAction))
addGestureRecognizer(panGesture)
}
@objc func gestureAction() {
print("gesture action")
}
}
The easiest way to do this is to add the gesture in a custom UITableViewCell
. An easier alternative to setting up a custom delegate pattern is to inform the view controller of the edits would be to use a handler in the form of a closure that the view controller can provide and which is called when user editing is finished. I'm assuming a textField is used to allow cell editing.
class CustomTableViewCell: UITableViewCell {
func activateTitleEditing() {
textField.isEnabled = true
textField.becomeFirstResponder()
}
// This will hold the handler closure which the view controller provides
var resignationHandler: (() -> Void)?
@objc private func tap(_ recognizer: UITapGestureRecognizer) {
guard recognizer.state == .ended else { return }
activateTitleEditing()
}
@IBOutlet weak var textField: UITextField! { didSet {
textField.delegate = self
let tap = UITapGestureRecognizer(target: self, action: #selector(tap(_:)))
addGestureRecognizer(tap)
textField.isEnabled = false
}}
}
extension CustomTableViewCell: UITextFieldDelegate {
func textFieldDidEndEditing(_ textField: UITextField) {
resignationHandler?()
}
}
And within your custom UITableViewController
, pass in the handler to be able to make changes to your model. Don't forget to account for possible memory cycles in the closure.
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
// initialize and return table view cell
let cell = tableView.dequeueReusableCell(withIdentifier: K.documentCellIdentifier, for: indexPath)
assert(cell is CustomTableViewCell, "Document cell dequeuing error")
let customCell = cell as! DocumentTableViewCell
customCell.textField.text = documentModel.documents[indexPath.row]
customCell.resignationHandler = { [weak self, unowned customCell] in
guard let self = self else { return }
if let newTitle = customCell.textField.text {
self.cellModel.cells[indexPath.row] = newTitle
}
}
return customCell
}
To add gesture to UITableViewCell, you can follow the steps below:
First, add gesture recognizer to UITableView
tapGesture = UITapGestureRecognizer(target: self, action: #selector(tableViewController.tapEdit(_:)))
tableView.addGestureRecognizer(tapGesture!)
tapGesture!.delegate = self
Then, define the selector. Use recognizer.locationInView
to locate the cell you tap in tableView. And you can access the data in your dataSource by tapIndexPath
, which is the indexPath of the cell the user tapped.
func tapEdit(recognizer: UITapGestureRecognizer) {
if recognizer.state == UIGestureRecognizerState.Ended {
let tapLocation = recognizer.locationInView(self.tableView)
if let tapIndexPath = self.tableView.indexPathForRowAtPoint(tapLocation) {
if let tappedCell = self.tableView.cellForRowAtIndexPath(tapIndexPath) as? MyTableViewCell {
//do what you want to cell here
}
}
}
}
It is possible to add gesture directly to TableView cell and access the datasource in viewController, You need to set up a delegate:
In your custom cell:
import UIKit
class MyTableViewCell: UITableViewCell {
var delegate: myTableDelegate?
override func awakeFromNib() {
super.awakeFromNib()
let tapGesture = UITapGestureRecognizer(target: self, action: #selector(MyTableViewCell.tapEdit(_:)))
addGestureRecognizer(tapGesture)
//tapGesture.delegate = ViewController()
}
func tapEdit(sender: UITapGestureRecognizer) {
delegate?.myTableDelegate()
}
}
protocol myTableDelegate {
func myTableDelegate()
}
In your viewController:
import UIKit
class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource, UIGestureRecognizerDelegate, myTableDelegate {
@IBOutlet var tableView: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
tableView.delegate = self
tableView.dataSource = self
// Do any additional setup after loading the view, typically from a nib.
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 35
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as? MyTableViewCell
cell?.delegate = self
return cell!
}
func myTableDelegate() {
print("tapped")
//modify your datasource here
}
}
However, this method could cause problems, see UIGestureRecognizer and UITableViewCell issue. In this case, when the swipe gesture successes, the selector get called twice for some reason. I can't say the second method is a bad one as I haven't found any direct evidence yet, but after searching through Google, it seems like the first method is the standard way.