UITableViewCell images disappear when scrolling - ios

Question

I have a UIButton inside a UITableViewCell where the image changes once the button is tapped. Though the selected buttons get selected as intended, once the UITableView scrolls, the selected images disappear since the cells are reused.
I'm having trouble writing the logic. Please help.
My code is below, in Swift 3.
CellForRow:
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
//Button_Action
addSongButtonIdentifier(cell: cell, indexPath.row)
}
This is where the cell is created:
func addSongButtonIdentifier(cell: UITableViewCell, _ index: Int) {
let addButton = cell.viewWithTag(TABLE_CELL_TAGS.addButton) as! UIButton
//accessibilityIdentifier is used to identify a particular element which takes an input parameter of a string
//assigning the indexpath button
addButton.accessibilityIdentifier = String (index)
// print("visible Index:",index)
print("Index when scrolling :",addButton.accessibilityIdentifier!)
addButton.setImage(UIImage(named: "correct"), for: UIControlState.selected)
addButton.setImage(UIImage(named: "add_btn"), for: UIControlState.normal)
addButton.isSelected = false
addButton.addTarget(self, action: #selector(AddToPlaylistViewController.tapFunction), for:.touchUpInside)
}
The tap function:
func tapFunction(sender: UIButton) {
print("IndexOfRow :",sender.accessibilityIdentifier!)
// if let seporated by a comma defines, if let inside a if let. So if the first fails it wont come to second if let
if let rowIndexString = sender.accessibilityIdentifier, let rowIndex = Int(rowIndexString) {
self.sateOfNewSongArray[rowIndex] = !self.sateOfNewSongArray[rowIndex]//toggle the state when tapped multiple times
}
sender.isSelected = !sender.isSelected //image toggle
print(" Array Data: ", self.sateOfNewSongArray)
selectedSongList.removeAll()
for (index, element) in self.sateOfNewSongArray.enumerated() {
if element{
print("true:", index)
selectedSongList.append(songDetailsArray[index])
print("selectedSongList :",selectedSongList)
}
}
}

Answer 1

There is logical error in func addSongButtonIdentifier(cell: UITableViewCell, _ index: Int) function at line addButton.isSelected = false
it should be addButton.isSelected = self.sateOfNewSongArray[index]
Since, cellForRowAtIndexpath method is called every time table is scrolled, it's resetting selected state of 'addButton'

Answer 2

You need to have array where you store which indexes are selected like selectedSongList array that you have. Then in your cellForRow method you need to use bool proparty from this array to give selected or deselected state to your button or in your addSongButtonIdentifier method selected state need to be
addButton.isSelected = selectedSongList.contains(indexPath.row)

Answer 3

Create a Model class for filling UITableView and take UIImage varaivals in that model, which will hold the current image for cell. On click on button action just change the UIImage variable with current image.

Answer 4

Best approach will be using a model class and keeping the track of each indiviual element in cell. But let me give you a quick fix.
Create a custom class of Button any where like this.
class classname: UIButton {
var imageName: String?
}
Go in your storyboard change the class from UIButton to classname
In your tableViewCellForIndexPath
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
let addButton = cell.viewWithTag(TABLE_CELL_TAGS.addButton) as! classname
if let imgName = addButton.imageName {
addButton.setImage(UIImage(named: imgName), for: UIControlState.normal)
} else {
addButton.setImage(UIImage(named: "add_btn"), for:UIControlState.normal)
}
addButton.addTarget(self, action: #selector(AddToPlaylistViewController.tapFunction), for:.touchUpInside)
return cell
}
Now let's move to your tapbutton implementation
func tapFunction(sender: classname) {
print("IndexOfRow :",sender.accessibilityIdentifier!)
// if let seporated by a comma defines, if let inside a if let. So if the first fails it wont come to second if let
if let rowIndexString = sender.accessibilityIdentifier, let rowIndex = Int(rowIndexString) {
self.sateOfNewSongArray[rowIndex] = !self.sateOfNewSongArray[rowIndex]//toggle the state when tapped multiple times
}
sender.imageName = sender.imageName == "correct" ? "add_btn" : "correct" //image toggle
sender.setImage(UIImage(named: sender.imageName), for:UIControlState.normal)
print(" Array Data: ", self.sateOfNewSongArray)
selectedSongList.removeAll()
for (index, element) in self.sateOfNewSongArray.enumerated() {
if element{
print("true:", index)
selectedSongList.append(songDetailsArray[index])
print("selectedSongList :",selectedSongList)
}
}
}