UICollectionView 自定义单元格在 Swift 中填充宽度

Question

I've been trying to figure-out how can i make the cell fill the width, as you can see in the picture the width between the cells is too big. i am using custom cell with only one imageView.

I tried to customize it from the storyboard but i guess there is no option for that or it should be done programmatically.

my UICollectionViewController :

 @IBOutlet var collectionView2: UICollectionView!

    let recipeImages = ["angry_birds_cake", "creme_brelee", "egg_benedict", "full_breakfast", "green_tea", "ham_and_cheese_panini", "ham_and_egg_sandwich", "hamburger", "instant_noodle_with_egg.jpg", "japanese_noodle_with_pork", "mushroom_risotto", "noodle_with_bbq_pork", "starbucks_coffee", "thai_shrimp_cake", "vegetable_curry", "white_chocolate_donut"]

    override func viewDidLoad() {
        super.viewDidLoad()

        // Uncomment the following line to preserve selection between presentations
        // self.clearsSelectionOnViewWillAppear = false

        // Do any additional setup after loading the view.

    }


    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

override func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
        //#warning Incomplete method implementation -- Return the number of sections
        return 1
    }


    override func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        //#warning Incomplete method implementation -- Return the number of items in the section
         return recipeImages.count
    }

    override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, forIndexPath: indexPath) as! RecipeCollectionViewCell

        // Configure the cell
        cell.recipeImageView.image = UIImage(named: recipeImages[indexPath.row])

        return cell
    }

Answer 1

You need to do this programatically.

Implement UICollectionViewDelegateFlowLayout in your view controller and provide the size in collectionView:layout:sizeForItemAtIndexPath:

func collectionView(_ collectionView: UICollectionView,
                        layout collectionViewLayout: UICollectionViewLayout,
                        sizeForItemAt indexPath: IndexPath) -> CGSize {
        let kWhateverHeightYouWant = 100
        return CGSizeMake(collectionView.bounds.size.width, CGFloat(kWhateverHeightYouWant))
}

You will also want to call collectionView.collectionViewLayout.invalidateLayout() inside your view controller's viewWillLayoutSubviews() so that when the main view's dimensions change (on rotation, for example), the collection view is re-laid out.

Swift 4 Update

func collectionView(_ collectionView: UICollectionView,
                            layout collectionViewLayout: UICollectionViewLayout,
                            sizeForItemAt indexPath: IndexPath) -> CGSize {
            let kWhateverHeightYouWant = 100
            return CGSize(width: collectionView.bounds.size.width, height: CGFloat(kWhateverHeightYouWant))
}

Answer 2

Inside your view controller override viewDidLayoutSubviews method

@IBOutlet weak var collectionView: UICollectionView!

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()

    if let layout = collectionView.collectionViewLayout as? UICollectionViewFlowLayout {
        let itemWidth = view.bounds.width / 3.0
        let itemHeight = layout.itemSize.height
        layout.itemSize = CGSize(width: itemWidth, height: itemHeight)
        layout.invalidateLayout()
    }
}

( collectionView property is your collectionView)

Answer 3

Use Following code for set the width of UICollectionViewCell .

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

Answer 4

Also in Swift 3,

Make sure your view controller complies with the following:

UICollectionViewDelegate,
UICollectionViewDataSource,
UICollectionViewDelegateFlowLayout

Answer 5

Swift 3

If you are using swift 3, use this method:

    func collectionView(_ collectionView: UICollectionView,
                        layout collectionViewLayout: UICollectionViewLayout,
                        sizeForItemAt indexPath: IndexPath) -> CGSize {

    }

Notice the changes:

1. add _ before collectionView in the method name
2. NSIndexPath changes to IndexPath

Answer 6

I have the same requirement, in my case below solution is worked. I set UIImageView top, left, bottom and right constraints to 0 inside UICollectionviewCell

@IBOutlet weak var imagesCollectionView: UICollectionView!

override func viewDidLoad() {
    super.viewDidLoad()
    // flowlayout
    let screenWidth = UIScreen.main.bounds.width
    let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
    layout.sectionInset = UIEdgeInsets(top: 5, left: 5, bottom: 10, right: 0)
    layout.itemSize = CGSize(width: screenWidth/3 - 5, height: screenWidth/3 - 5)
    layout.minimumInteritemSpacing = 5
    layout.minimumLineSpacing = 5
    imagesCollectionView.collectionViewLayout = layout

}

Answer 7

For my case, I wanted to show two columns and 3 rows in the UICollectionView

I added UICollectionViewDelegateFlowLayout delegate to my class

then I override sizeForItemAt indexPath

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    let cellHeight = (collectionView.bounds.size.height - 30) / 3 // 3 count of rows to show
    let cellWidth = (collectionView.bounds.size.width - 20) / 2 // 2 count of colomn to show
    return CGSize(width: CGFloat(cellWidth), height: CGFloat(cellHeight))
}

The 30 is the Line spacing, the 20 is the insent between cells

Answer 8

以编程方式将itemSize设置为[UIScreen mainScreen].bounds.size.width/3

Answer 9

In my case, assuming every cell has a width of 155 and a height of 220. If I want to show 2 cells per row in a portrait mode and 3 for landscape.

func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
    var itemsCount : CGFloat = 2.0
    if UIApplication.sharedApplication().statusBarOrientation != UIInterfaceOrientation.Portrait {
        itemsCount = 3.0
    }
    return CGSize(width: self.view.frame.width/itemsCount - 20, height: 220/155 * (self.view.frame.width/itemsCount - 20));
}

Answer 10

The best solution is to change the itemSize of your UICollectionViewFlowLayout in viewDidLayoutSubviews . That is where you can get the most accurate size of the UICollectionView . You don't need to call invalidate on your layout, that will be done for you already.

Answer 11

For my case, autolayout was only allowing the cell to grow to its content size even though I overrode the cell size in the storyboard, conformed to UICollectionViewDelegateFlowLayout , and implemented sizeForItemAt . So I made a dummy UIView the width of the cell's bounds.

UICollectionViewController:

extension CollectionViewController: UICollectionViewDelegateFlowLayout {
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        let width = collectionView.bounds.width - 40
        return CGSize(width: width, height: collectionView.bounds.height / 3)
    }
}

Cell (I'm calling this method on dependency injection):

private func updateViews() {
    let padding:CGFloat = 8
    let innerView = UIView()
    innerView.translatesAutoresizingMaskIntoConstraints = false
    innerView.layer.cornerRadius = 8
    innerView.layer.borderColor = UIColor.black.cgColor
    innerView.layer.borderWidth = 1
    contentView.addSubview(innerView)
    NSLayoutConstraint.activate([
        innerView.widthAnchor.constraint(equalToConstant: bounds.width - padding*2),
        innerView.leadingAnchor.constraint(equalTo: safeAreaLayoutGuide.leadingAnchor, constant: padding),
        innerView.trailingAnchor.constraint(equalTo: safeAreaLayoutGuide.trailingAnchor, constant: -padding),
        innerView.topAnchor.constraint(equalTo: safeAreaLayoutGuide.topAnchor, constant: padding),
        innerView.bottomAnchor.constraint(equalTo: safeAreaLayoutGuide.bottomAnchor, constant: -padding)
    ])
}