How do i reference a specific cell's data in its delegate?

Question

I am just starting with delegates in Swift. I have a collectionView that will be populated with specifc cells. Every cell will have a like button were a user can press it, every press should toggle between two different heart images. I have setup the delegate and its protocol in the cell class. I call the delegate in the view controller class that holds the collection of the cells. How I am supposed to change the specific cell's heart-button-image if it does not let me reference the cell and its properties? Thank you!!

I obviously have tried calling the IB Action heart-button-image variable, no luck. do I need to just merge my delegate with the: "func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell" function? This does of course allow you to reference the specific cell but it seems like the wrong approach.

CUSTOM CELL CLASS THAT HOLDS DELEGATE INITILIZATION:

 protocol EventCellDelegate: class {
func likeButtonPressed(toggle: Int)
}

class ProfileEventCollectionViewCell: UICollectionViewCell {

@IBOutlet weak var likeCount: UILabel!
@IBOutlet weak var friendsGoing: UILabel!
@IBOutlet weak var friendGoingPic: UIImageView!
@IBOutlet weak var eventName: UILabel!
@IBOutlet weak var eventDate: UILabel!
@IBOutlet weak var eventTime: UILabel!
@IBOutlet weak var eventOrg: UILabel!
@IBOutlet weak var eventPic: UIImageView!
@IBOutlet weak var eventPrice: UIButton! // WHERE THE HEART IMAGE         GOES (bad name sorry)

weak var delegate: EventCellDelegate?
var likeToggle = 1
/*
let redHeart = UIImage(named: "likeheart")
let grayHeart = UIImage(named: "unlikeheart")
var likeToggle  = 1
var likeCountValue = 347
*/

@IBAction func eventPricePressed(_ sender: UIButton) {

    delegate?.likeButtonPressed(toggle: 1)
}
}

DELEGATE FUNCTION INSIDE MY HOME VIEW CONTROLLER CLASS:

extension HomeViewController: EventCellDelegate {
func likeButtonPressed(toggle: Int) {
    //ProfileEventCollectionViewCell.eventPrice  <-- doesnt allow
        likeToggle = likeToggle + toggle          <-- doesnt find
        likeToggle
    if (likeToggle % 2 == 0) {
        eventPrice.setImage(redHeart, for: .normal)
        //likeCountValue = likeCountValue + 1
    } else {
        eventPrice.setImage(grayHeart, for: .normal)
        //likeCountValue = likeCountValue - 1

    }
}

}

Instance member 'eventPrice' cannot be used on type 'ProfileEventCollectionViewCell'

Use of unresolved identifier 'likeToggle'

Paulw11 Paulw11 · Accepted Answer · 2019-06-27T02:11:22

Your delegate function needs to pass the cell in which the like button was pressed:

protocol EventCellDelegate: class {
    func likeButtonPressed(in cell: ProfileEventCollectionViewCell)
}

Then you can call the delegate function as:

@IBAction func eventPricePressed(_ sender: UIButton) {
    delegate?.likeButtonPressed(in:self)
}

You don't need to pass the toggle value - The view controller can decide what it needs to do when the button is tapped.

I wouldn't update the cell directly in the delegate method; Update your data model and then reload the cell - your cellForItemAt: can handle the appearance update.

And your implementation of the delegate function will be something like:

func likeButtonPressed(in cell:ProfileEventCollectionViewCell) {

    guard let indexPath = self.collectionView.indexPath(for: cell) else {
        return
    }

    let myObject = myDataSource[indexPath.item]
    myObject.liked.toggle
    self.collectionView.reloadItems(at: [indexPath])
}

How do i reference a specific cell's data in its delegate?

1 Answers