How to set UICollectionViewCell Width and Height programmatically

Question

I am trying to implement a CollectionView. When I am using Autolayout, my cells won\'t change the size, but their alignment.

Now I would rather want to

Answer 1

**Swift 5**
To make this work you have to do the following.

Add these protocols

 - UICollectionViewDelegate


 - UICollectionViewDataSource


 - UICollectionViewDelegateFlowLayout

Your code will then look like this

extension YourViewController: UICollectionViewDelegate {
    //Write Delegate Code Here
}

extension YourViewController: UICollectionViewDataSource {
    //Write DataSource Code Here
}

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

Now the final and crucial step to see this take effect is to go to your viedDidLoad function inside your Viewcontroller.

    override func viewDidLoad() {
        super.viewDidLoad()
        collection.dataSource = self // Add this
        collection.delegate = self // Add this

        // Do any additional setup after loading the view.
    }

Without telling your view which class the delegate is it won't work.