集合视图单元格不会改变大小

Question

I am trying to create an application with a collection view. No matter what I do, I cannot change its size. In the view controller, it looks larger than when program is ran (photos below). The image view is the same size as the cell. I have also tried using

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
         return CGSize(width: screenWidth/3, height: screenWidth/3)
    }

But nothing changes.

Here is the viewcontroller code:

import UIKit

class ViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource {

    let array = ["1,", "2", "3", "4", "5", "6", "7", "8", "9", "10"]

    override func viewDidLoad() {
        super.viewDidLoad()
    }

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

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! myCell
        cell.myImageView.image = UIImage(named: array[indexPath.row] + ".jpg")

        return cell
    }

}

myCell is just a UICollectionViewCell class with an outlet to the imageview.

Answer 1

To call the sizeForItemAt method, make sure that your class adopts both UICollectionViewDelegate and UICollectionViewDelegateFlowLayout protocols.

Answer 2

You have to use this function in your viewController

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {        
        return CGSize(width: UIScreen.main.bounds.height, height: <Desired Height>)
    }
}