CODEWITHSUNDEEP
iosswiftuicollectionviewuikit
Nime Zoste
Nime Zoste

Reputation: 37

UICollectionViewFlowLayout, UICollectionView: changing screen orientation breaks cells arrangement

let numberOfCellsPerRow: CGFloat = 3

override func viewDidLoad() {
    super.viewDidLoad()

    layout = UICollectionViewFlowLayout()
    layout.minimumLineSpacing = 0
    layout.minimumInteritemSpacing = 0

    collectionView = UICollectionView(frame: CGRect(x: 0, y: 0, width: view.frame.width, height: view.frame.height), collectionViewLayout: layout)
    collectionView.backgroundColor = .clear
    collectionView.dataSource = self
    collectionView.delegate = self
    collectionView.register(UICollectionViewCell.self, forCellWithReuseIdentifier: "cell")

    view.addSubview(collectionView)
}

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return 3
}

func numberOfSections(in collectionView: UICollectionView) -> Int {
    return 1
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    let cellWidth = (view.frame.width - max(0, numberOfCellsPerRow - 1) * layout.minimumInteritemSpacing) / numberOfCellsPerRow

    return CGSize(width: cellWidth, height: 75.0)
}

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let itemCell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath)
    itemCell.backgroundColor = .black

    return itemCell
}

Vertical Orientation Vertical Orientation

Horizontal Orientation Horizontal Orientation

I'm expecting all cells on the same row. Why there is some margin on the left side of the first cell (horizontal orientation)? In the case when I'm launching the application with horizontal orientation, some space appears between cells in vertical orientation.

Upvotes: 1

Views: 439

Answers (1)

Shehata Gamal
Shehata Gamal

Reputation: 100503

You can try to use auto-layout

self.collectionView.translatesAutoresizingMaskIntoConstraints = false

NSLayoutConstraint.activate([

    self.collectionView.leadingAnchor.constraint(equalTo: self.view.leadingAnchor),
    self.collectionView.trailingAnchor.constraint(equalTo: self.view.trailingAnchor),
    self.collectionView.topAnchor.constraint(equalTo: self.view.topAnchor),
    self.collectionView.bottomAnchor.constraint(equalTo: self.view.bottomAnchor),

])

Or refresh the frame inside viewWillTransition 

override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {

    super.viewWillTransition(to: size, with: coordinator)

    self.collectionView.frame = CGRect(x: 0, y: 0, width: view.frame.width, height: view.frame.height)

    self.collectionView.collectionViewLayout.invalidateLayout()

}

Upvotes: 1

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