How to set cell spacing and UICollectionView - UICollectionViewFlowLayout size ratio

Question

I m trying to add UICollectionView to ViewController  and I need to have 3 cells  per row  without blank space between cells  it should look like a grid   Cell width should be one third of screen size  so I thought that the layout item width should be the same  But then I get this     If I reduce that size  by 7 or 8 pixels e g    it s better  but the  third cell in row is not completely visible  and I still have that blank space  top  amp  bottom  and left  amp  right       class ViewController  UIViewController  UICollectionViewDelegateFlowLayout  UICollectionViewDataSource       var collectionView  UICollectionView      var screenSize  CGRect      var screenWidth  CGFloat      var screenHeight  CGFloat       override func viewDidLoad             super viewDidLoad            screenSize   UIScreen mainScreen   bounds         screenWidth   screenSize width         screenHeight   screenSize height             Do any additional setup after loading the view  typically from a nib         let layout  UICollectionViewFlowLayout   UICollectionViewFlowLayout           layout sectionInset   UIEdgeInsets top  20  left  0  bottom  10  right  0          layout itemSize   CGSize width  screenWidth   3  height  screenWidth   3          collectionView   UICollectionView frame  self view frame  collectionViewLayout  layout          collectionView  dataSource   self         collectionView  delegate   self         collectionView  registerClass CollectionViewCell self  forCellWithReuseIdentifier   CollectionViewCell           collectionView  backgroundColor   UIColor greenColor           self view addSubview collectionView              func numberOfSectionsInCollectionView collectionView  UICollectionView  - gt  Int           return 1            func collectionView collectionView  UICollectionView  numberOfItemsInSection section  Int  - gt  Int           return 20            func collectionView collectionView  UICollectionView  cellForItemAtIndexPath indexPath  NSIndexPath  - gt  UICollectionViewCell           let cell   collectionView dequeueReusableCellWithReuseIdentifier  CollectionViewCell   forIndexPath  indexPath  as CollectionViewCell         cell backgroundColor   UIColor whiteColor           cell layer borderColor   UIColor blackColor   CGColor         cell layer borderWidth   0 5         cell frame size width   screenWidth   3         cell frame size height   screenWidth   3          cell textLabel  text      indexPath section    indexPath row           return cell

User · Answer

let layout   myCollectionView collectionViewLayout as  UICollectionViewFlowLayout layout  minimumLineSpacing   8

User · Answer

If you are looking for Swift 3  Follow the steps to achieve this   func viewDidLoad            Define Layout here     let layout  UICollectionViewFlowLayout   UICollectionViewFlowLayout          Get device width     let width   UIScreen main bounds width        set section inset as per your requirement      layout sectionInset   UIEdgeInsets top  0  left  5  bottom  0  right  5         set cell item size here      layout itemSize   CGSize width  width   2  height  width   2         set Minimum spacing between 2 items     layout minimumInteritemSpacing   0        set minimum vertical line spacing here between two lines in collectionview     layout minimumLineSpacing   0        apply defined layout to collectionview     collectionView  collectionViewLayout   layout      This is verified on Xcode 8 0 with Swift 3

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Add these 2 lines    layout minimumInteritemSpacing   0 layout minimumLineSpacing   0   So you have         Do any additional setup after loading the view  typically from a nib          let layout  UICollectionViewFlowLayout   UICollectionViewFlowLayout           layout sectionInset   UIEdgeInsets top  20  left  0  bottom  10  right  0          layout itemSize   CGSize width  screenWidth 3  height  screenWidth 3          layout minimumInteritemSpacing   0         layout minimumLineSpacing   0         collectionView  collectionViewLayout   layout   That will remove all the spaces and give you a grid layout     If you want the first column to have a width equal to the screen width then add the following function   func collectionView collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  sizeForItemAtIndexPath indexPath  NSIndexPath  - gt  CGSize       if indexPath row    0               return CGSize width  screenWidth  height  screenWidth 3            return CGSize width  screenWidth 3  height  screenWidth 3        Grid layout will now look like  I ve also added a blue background to first cell

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Swift 5   For evenly distributed spaces between cells with dynamic cell width to make the best of container space you may use the code snippet below by providing a minimumCellWidth value  private func collectionViewLayout   - gt  UICollectionViewLayout            let layout   UICollectionViewFlowLayout       layout sectionHeadersPinToVisibleBounds   true        Important  if direction is horizontal use minimumItemSpacing instead       layout scrollDirection    vertical          let itemHeight  CGFloat   240     let minCellWidth  CGFloat   130 0     let minItemSpacing  CGFloat   10     let containerWidth  CGFloat   self view bounds width     let maxCellCountPerRow  CGFloat    floor  containerWidth - minItemSpacing     minCellWidth minItemSpacing             let itemWidth  CGFloat   floor    containerWidth -  2   minItemSpacing  -  maxCellCountPerRow-1    minItemSpacing    maxCellCountPerRow             Calculate the remaining space after substracting calculating cellWidth  Divide by 2 because of left and right insets      let inset   max minItemSpacing  floor   containerWidth -  maxCellCountPerRow itemWidth  -  maxCellCountPerRow-1  minItemSpacing    2               layout itemSize   CGSize width  itemWidth  height  itemHeight      layout minimumInteritemSpacing   min minItemSpacing inset      layout minimumLineSpacing   minItemSpacing     layout sectionInset   UIEdgeInsets top  minItemSpacing  left  inset  bottom  minItemSpacing  right  inset            return layout

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For Swift 3  and Xcode 9  Try using this   extension ViewController  UICollectionViewDelegateFlowLayout    func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  sizeForItemAt indexPath  IndexPath  - gt  CGSize        let collectionWidth   collectionView bounds width     return CGSize width  collectionWidth 3  height  collectionWidth 3      func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  minimumLineSpacingForSectionAt section  Int  - gt  CGFloat       return 0    func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  minimumInteritemSpacingForSectionAt section  Int  - gt  CGFloat       return 0

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Swift 4  let collectionViewLayout   collectionView collectionViewLayout as  UICollectionViewFlowLayout collectionViewLayout  sectionInset   UIEdgeInsetsMake 0  20  0  40   collectionViewLayout  invalidateLayout

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In Certain situations  Setting the UICollectionViewFlowLayout in viewDidLoador ViewWillAppear may not effect on the collectionView   Setting the UICollectionViewFlowLayout in viewDidAppear may cause see the changes of the cells sizes in runtime   Another Solution  in Swift 3    extension YourViewController   UICollectionViewDelegateFlowLayout       func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  insetForSectionAt section  Int  - gt  UIEdgeInsets           return UIEdgeInsets top  20  left  0  bottom  10  right  0             func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  sizeForItemAt indexPath  IndexPath  - gt  CGSize           let collectionViewWidth   collectionView bounds width         return CGSize width  collectionViewWidth 3  height  collectionViewWidth 3             func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  minimumInteritemSpacingForSectionAt section  Int  - gt  CGFloat           return 0           func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  minimumLineSpacingForSectionAt section  Int  - gt  CGFloat           return 20

User · Answer

For Swift 3 and XCode 8  this worked  Follow below steps to achieve this -  viewDidLoad                 let layout  UICollectionViewFlowLayout   UICollectionViewFlowLayout           var width   UIScreen main bounds width         layout sectionInset   UIEdgeInsets top  0  left  5  bottom  0  right  5      width   width - 10     layout itemSize   CGSize width  width   2  height  width   2          layout minimumInteritemSpacing   0         layout minimumLineSpacing   0         collectionView  collectionViewLayout   layout

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For Swift 3 and XCode 8  this worked  Follow below steps to achieve this -        let layout  UICollectionViewFlowLayout   UICollectionViewFlowLayout       let width   UIScreen main bounds width     layout sectionInset   UIEdgeInsets top  0  left  5  bottom  0  right  5      layout itemSize   CGSize width  width   2  height  width   2      layout minimumInteritemSpacing   0     layout minimumLineSpacing   0     collectionView  collectionViewLayout   layout     Place this code into viewDidLoad   function

[swift] How to set cell spacing and UICollectionView - UICollectionViewFlowLayout size ratio?

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