swift - right to left horizontal collection view in displayed incorrectly from left to right

Question

I'm displaying a horizontal collection view from right to left and encountering a problem that when displaying the elements, they are displayed from the end (left to right instead):

• In the run schema options, the app language is set as right to left pseudo language
• If I'm adding the items when starting the app before instead of adding them after and calling reloadData, the problem doesn't occur
• Sample project and screenshots are attached

One solution proposed was adding the code below that worked but required me to reverse the order to add the items. I would like to know if there's a better way to do it and also within the API instead of using an overriding extension

extension UICollectionViewFlowLayout {

open override var flipsHorizontallyInOppositeLayoutDirection: Bool {
    return true
}

}

sample project

help would be appreciated

code:

import UIKit

class HorizontalScrollTestViewController: UIViewController, UICollectionViewDataSource , CellDelegate{


    var items = [String]()

@IBOutlet weak var collectionView: UICollectionView!



func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return items.count
}

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "ReusableCell", for: indexPath) as! CategoryCollectionViewCell

    cell.category.setTitle(items[indexPath.row] , for: UIControl.State.normal)
    cell.delegate = self
    return cell

}



override func viewDidLoad() {
    super.viewDidLoad()

    let dispatchQueue = DispatchQueue(label: "resourcesQueue", qos: .background)
    dispatchQueue.async {
        self.addItems()

        DispatchQueue.main.async {
            self.collectionView.reloadData()
        }

    }
    collectionView.dataSource = self

    collectionView?.register(UINib(nibName: "CategoryCollectionViewCell", bundle: nil), forCellWithReuseIdentifier: "ReusableCell")


}

func buttonPressed(_ cell: UICollectionViewCell) {
    if  let row = self.collectionView.indexPath(for: cell)?.row {
        print(items[row])
    }
}


func addItems() {
    self.items.append("test 10")
    self.items.append("test 9")
    self.items.append("test 8")
    self.items.append("test 7")
    self.items.append("test 6")
    self.items.append("test 5")
    self.items.append("test 4")
    self.items.append("test 3")
    self.items.append("test 2")
    self.items.append("test 1")



 }
}

example when adding the items after the app started and using reloadData:

expected behavior

Answer 1

Here you just flip your collectionView and collectionViewCell horizontally. this will solve your issue.

With this you can flip your collectionView horizontally. so that your collectionView starts from right. your first element will be at right and last element will be at left.

collectionView.transform = CGAffineTransform(scaleX: -1, y: 1)

OR

collectionView.transform = CGAffineTransform(a: -1.0, b: 0.0, c: 0.0, d: 1.0, tx: 0.0, ty: 0.0)

Similarly you have to flip each collectionViewCell also using

cell.transform = CGAffineTransform(scaleX: -1, y: 1)

OR

cell.transform = CGAffineTransform(a: -1.0, b: 0.0, c: 0.0, d: 1.0, tx: 0.0, ty: 0.0)

and add element in array in following order

func addItems() {
        self.items.append("test 1")
        self.items.append("test 2")
        self.items.append("test 3")
        self.items.append("test 4")
        self.items.append("test 5")
        self.items.append("test 6")
        self.items.append("test 7")
        self.items.append("test 8")
        self.items.append("test 9")
        self.items.append("test 10")
    }

Download updated project from Here