Current Index associating with wrong data - ios

Question

I have a collection view that scrolls horizontally and each cell pushes to a detail view upon a tap. When I load the app, I have it print the object at index. At first it will load the one cell it is supposed to. But when I scroll over one space it prints off two new ids, and then begins to associate the data of the last loaded cell with the one currently on the screen, which is off by one spot now. I have no clue how to resolve this, my best guess is there is some way to better keep up with the current index or there is something in the viewDidAppear maybe I am missing. Here is some code:
open var currentIndex: Int {
guard (self.collectionView) != nil else { return 0 }
return Int()
}
public func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "ExpandCell", for: indexPath) as! ExpandingCollectionViewCell
let object = self.imageFilesArray[(indexPath).row] as! PFObject
cell.nameLabel.text = object["Name"] as! String
whatObject = String(describing: object.objectId)
print(whatObject)
return cell
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
let object = self.imageFilesArray[(indexPath as NSIndexPath).row]
guard let cell = collectionView.cellForItem(at: indexPath) as? ExpandingCollectionViewCell else { return }
let storyBoard : UIStoryboard = UIStoryboard(name: "Main", bundle:nil)
let nextViewController = storyBoard.instantiateViewController(withIdentifier: "EventDetailViewController") as! EventDetailViewController
nextViewController.lblName = nameData
nextViewController.whatObj = self.whatObject
self.present(nextViewController, animated:false, completion:nil)
}
Does anyone know a better way to set the current index so I am always pushing the correct data to the next page?

Answer 1

The data source that is setting the elements of the cell can keep count of index that can also be set as a property and can be used to retrieve back from the cell to get correct current index.

Answer 2

EventDetailViewController is your UICollectionViewController subclass I assume.
If this is correct then you need to implement on it:
A method that tells the collection how many items there are in the datasource.
//1
override func numberOfSections(in collectionView: UICollectionView) -> Int {
return 1 // you only have 1 section
}
//2
override func collectionView(_ collectionView: UICollectionView,
numberOfItemsInSection section: Int) -> Int {
return array.count// this is the number of models you have to display... they will all live in one section
}
A method that tells the collection which cellView subclass to use for that given row.
-A method that populates the cell with it's datasource.
Follow this tutorial from which I extracted part of the code, they convey this core concepts pretty clearly.
Reusing, as per Apple's docs happens for a number of cells decided by UIKit, when you scroll up a little bit 2 or N cells can be dequed for reusing.
In summary, with this three methods you can offset your collection into skipping the one record that you want to avoid.
Happy coding!