UICollectionView Set number of columns

Question

I just started learning about UICollectionViews  I m wondering if anyone knows how to specify the number of columns in a collectionview  The default is set to 3  iPhone portrait   I ve looked at the documentation and can t seem to find a concise answer

User · Answer

First add UICollectionViewDelegateFlowLayout as protocol   Then   func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  sizeForItemAt indexPath  IndexPath  - gt  CGSize           var columnCount   3         let width     view frame width - 20    columnCount         return CGSize width  width  height  width

User · Answer

This answer is for swift 3 0 --   first conform to the protocol     UICollectionViewDelegateFlowLayout   then add these methods          this method is for the size of items           func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  sizeForItemAt indexPath  IndexPath  - gt  CGSize           let width   collectionView frame width 3         let height   CGFloat   160 0         return CGSize width  width  height  height              these methods are to configure the spacing between items      func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  insetForSectionAt section  Int  - gt  UIEdgeInsets           return UIEdgeInsetsMake 0 0 0 0             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 0

User · Answer

Its all about layout you want to draw  You can create custom class inheriting from UICollectionViewFlowLayout  Currently there is not any direct method to set columns  If you want to achieve this kind of functionality you need to do it manually  You need to handle it in your custom flow layout class    Now question will arise how you will do it  If you dont want to disturb cell frame you can adjust    collectionView layout minimumInteritemSpacingForSectionAtIndex   collectionView layout minimumLineSpacingForSectionAtIndex    Another way is provide you own positions of cells  By overriding below two methods  which will get called during your layout formation      -  NSArray  layoutAttributesForElementsInRect  CGRect rect   -  UICollectionViewLayoutAttributes   layoutAttributesForItemAtIndexPath  NSIndexPath   path   UICollectionViewLayoutAttributes is class which will deal with cell position  frame  Zindex etc

User · Answer

CollectionViews are very powerful  and they come at a price  Lots  and lots of options  As omz said      there are multiple ways you could change the number of columns   I d suggest implementing the  lt UICollectionViewDelegateFlowLayout gt  Protocol  giving you access to the following methods in which you can have greater control over the layout of your UICollectionView  without the need for subclassing it    collectionView layout insetForSectionAtIndex  collectionView layout minimumInteritemSpacingForSectionAtIndex  collectionView layout minimumLineSpacingForSectionAtIndex  collectionView layout referenceSizeForFooterInSection  collectionView layout referenceSizeForHeaderInSection  collectionView layout sizeForItemAtIndexPath    Also  implementing the following method will force your UICollectionView to update it s layout on an orientation change   say you wanted to re-size the cells for landscape and make them stretch   - void willRotateToInterfaceOrientation  UIInterfaceOrientation toInterfaceOrientation                                duration  NSTimeInterval duration        self myCollectionView collectionViewLayout invalidateLayout       Additionally  here are 2 really good tutorials on UICollectionViews   http   www raywenderlich com 22324 beginning-uicollectionview-in-ios-6-part-12  http   skeuo com uicollectionview-custom-layout-tutorial

User · Answer

Updated to Swift 3   Instead of the flow layout  I prefer using custom layout for specific column number and row number  Because    It can be dragged horizontally if column number is very big  It is more acceptable logically because of using column and row    Normal cell and Header cell   Add UILabel as a IBOutlet to your xib    class CollectionViewCell  UICollectionViewCell     IBOutlet weak var label  UILabel   override func awakeFromNib         super awakeFromNib          Initialization code     self backgroundColor   UIColor black     label textColor   UIColor white      class CollectionViewHeadCell  UICollectionViewCell     IBOutlet weak var label  UILabel   override func awakeFromNib         super awakeFromNib          Initialization code     self backgroundColor   UIColor darkGray     label textColor   UIColor white       Custom layout   let cellHeight  CGFloat   100 let cellWidth  CGFloat   100  class CustomCollectionViewLayout  UICollectionViewLayout       private var numberOfColumns  Int      private var numberOfRows  Int          It is two dimension array of itemAttributes     private var itemAttributes     UICollectionViewLayoutAttributes            It is one dimension of itemAttributes     private var cache    UICollectionViewLayoutAttributes     override func prepare         if self cache isEmpty            self numberOfColumns   self collectionView  numberOfItems inSection  0          self numberOfRows   self collectionView  numberOfSections             Dynamically change cellWidth if total cell width is smaller than whole bounds            if  self collectionView  bounds size width   CGFloat self numberOfColumns   gt  cellWidth            self cellWidth    self collectionView  bounds size width   CGFloat self numberOfColumns                                 for row in 0   lt self numberOfRows               var row temp    UICollectionViewLayoutAttributes                for column in 0   lt self numberOfColumns                    let indexPath   NSIndexPath item  column  section  row                   let attributes   UICollectionViewLayoutAttributes forCellWith  indexPath as IndexPath                  attributes frame   CGRect x  cellWidth CGFloat column   y  cellHeight CGFloat row   width  cellWidth  height  cellHeight                   row temp append attributes                   self cache append attributes                            self itemAttributes append row temp                    override var collectionViewContentSize  CGSize       return CGSize width  CGFloat self numberOfColumns  cellWidth  height  CGFloat self numberOfRows  cellHeight     override func layoutAttributesForElements in rect  CGRect  - gt   UICollectionViewLayoutAttributes          var layoutAttributes    UICollectionViewLayoutAttributes         for attributes in cache           if attributes frame intersects rect                layoutAttributes append attributes                      return layoutAttributes       CollectionView   let CellIdentifier    CellIdentifier  let HeadCellIdentifier    HeadCellIdentifier   class CollectionView  UICollectionView  UICollectionViewDelegate  UICollectionViewDataSource    init         let layout   CustomCollectionViewLayout        super init frame  CGRect zero  collectionViewLayout  layout       self register UINib nibName   CollectionViewCell   bundle  nil   forCellWithReuseIdentifier  CellIdentifier      self register UINib nibName   CollectionViewHeadCell   bundle  nil   forCellWithReuseIdentifier  HeadCellIdentifier       self isDirectionalLockEnabled   true     self dataSource   self     self delegate   self    required init  coder aDecoder  NSCoder        fatalError  init coder   has not been implemented      func updateCollectionView         DispatchQueue main async           self reloadData               MARK  CollectionView datasource func collectionView   collectionView  UICollectionView  numberOfItemsInSection section  Int  - gt  Int       return 20   func numberOfSections in collectionView  UICollectionView  - gt  Int       return 20   override func numberOfItems inSection section  Int  - gt  Int       return 20   func collectionView   collectionView  UICollectionView  cellForItemAt indexPath  IndexPath  - gt  UICollectionViewCell        let column    indexPath as NSIndexPath  row     let row    indexPath as NSIndexPath  section      if column    0           let cell   CollectionViewHeadCell   collectionView dequeueReusableCell withReuseIdentifier  HeadCellIdentifier  for  indexPath  as  CollectionViewHeadCell          cell label text      row            return cell           else if row    0           let cell   CollectionViewHeadCell   collectionView dequeueReusableCell withReuseIdentifier  HeadCellIdentifier  for  indexPath  as  CollectionViewHeadCell          cell label text      column            return cell           else           let cell   CollectionViewCell   collectionView dequeueReusableCell withReuseIdentifier  CellIdentifier  for  indexPath  as  CollectionViewCell          cell label text   String format    d   arguments   indexPath section indexPath row            return cell             MARK  CollectionView delegate func collectionView   collectionView  UICollectionView  didSelectItemAt indexPath  IndexPath         let column    indexPath as NSIndexPath  row     let row    indexPath as NSIndexPath  section      print    column     row          Use CollectionView from ViewController   class ViewController  UIViewController   let collectionView   CollectionView    override func viewDidLoad         collectionView translatesAutoresizingMaskIntoConstraints   false     self view addSubview collectionView      self view backgroundColor   UIColor red      self view addConstraints NSLayoutConstraint constraints withVisualFormat   H   collectionView     options      metrics  nil  views    collectionView   collectionView        self view addConstraints NSLayoutConstraint constraints withVisualFormat   V   collectionView     options      metrics  nil  views    collectionView   collectionView       override func viewDidAppear   animated  Bool        super viewDidAppear animated       collectionView updateCollectionView         Finally you can have fancy CollectionView

User · Answer

Updated to  Swift 5  iOS 13  Collectionview Estimate Size must be none    Declare margin for cell  let margin  CGFloat   10   In viewDidLoad configure minimumInteritemSpacing  minimumLineSpacing  sectionInset   guard let collectionView   docsColl  let flowLayout   collectionView collectionViewLayout as  UICollectionViewFlowLayout else   return        flowLayout minimumInteritemSpacing   margin     flowLayout minimumLineSpacing   margin     flowLayout sectionInset   UIEdgeInsets top  margin  left  margin  bottom  margin  right  margin    UICollectionViewDataSource method sizeForItemAt  func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  sizeForItemAt indexPath  IndexPath  - gt  CGSize        let noOfCellsInRow   2     number of column you want     let flowLayout   collectionViewLayout as  UICollectionViewFlowLayout     let totalSpace   flowLayout sectionInset left           flowLayout sectionInset right            flowLayout minimumInteritemSpacing   CGFloat noOfCellsInRow - 1        let size   Int  collectionView bounds width - totalSpace    CGFloat noOfCellsInRow       return CGSize width  size  height  size

User · Answer

With Swift 5 and iOS 12 3  you can use one the 4 following implementations in order to set the number of items per row in your UICollectionView while managing insets and size changes  including rotation       1  Subclassing UICollectionViewFlowLayout and using UICollectionViewFlowLayout s itemSize property  ColumnFlowLayout swift   import UIKit  class ColumnFlowLayout  UICollectionViewFlowLayout        let cellsPerRow  Int      init cellsPerRow  Int  minimumInteritemSpacing  CGFloat   0  minimumLineSpacing  CGFloat   0  sectionInset  UIEdgeInsets    zero            self cellsPerRow   cellsPerRow         super init            self minimumInteritemSpacing   minimumInteritemSpacing         self minimumLineSpacing   minimumLineSpacing         self sectionInset   sectionInset            required init  coder aDecoder  NSCoder            fatalError  init coder   has not been implemented              override func prepare             super prepare            guard let collectionView   collectionView else   return           let marginsAndInsets   sectionInset left   sectionInset right   collectionView safeAreaInsets left   collectionView safeAreaInsets right   minimumInteritemSpacing   CGFloat cellsPerRow - 1          let itemWidth     collectionView bounds size width - marginsAndInsets    CGFloat cellsPerRow   rounded  down          itemSize   CGSize width  itemWidth  height  itemWidth             override func invalidationContext forBoundsChange newBounds  CGRect  - gt  UICollectionViewLayoutInvalidationContext           let context   super invalidationContext forBoundsChange  newBounds  as  UICollectionViewFlowLayoutInvalidationContext         context invalidateFlowLayoutDelegateMetrics   newBounds size    collectionView  bounds size         return context            CollectionViewController swift   import UIKit  class CollectionViewController  UICollectionViewController        let columnLayout   ColumnFlowLayout          cellsPerRow  5          minimumInteritemSpacing  10          minimumLineSpacing  10          sectionInset  UIEdgeInsets top  10  left  10  bottom  10  right  10             override func viewDidLoad             super viewDidLoad            collectionView  collectionViewLayout   columnLayout         collectionView  contentInsetAdjustmentBehavior    always         collectionView  register UICollectionViewCell self  forCellWithReuseIdentifier   Cell              override func collectionView   collectionView  UICollectionView  numberOfItemsInSection section  Int  - gt  Int           return 59            override func collectionView   collectionView  UICollectionView  cellForItemAt indexPath  IndexPath  - gt  UICollectionViewCell           let cell   collectionView dequeueReusableCell withReuseIdentifier   Cell   for  indexPath          cell backgroundColor   UIColor orange         return cell                 2  Using UICollectionViewFlowLayout s itemSize method  import UIKit  class CollectionViewController  UICollectionViewController        let margin  CGFloat   10     let cellsPerRow   5      override func viewDidLoad             super viewDidLoad            guard let collectionView   collectionView  let flowLayout   collectionViewLayout as  UICollectionViewFlowLayout else   return            flowLayout minimumInteritemSpacing   margin         flowLayout minimumLineSpacing   margin         flowLayout sectionInset   UIEdgeInsets top  margin  left  margin  bottom  margin  right  margin           collectionView contentInsetAdjustmentBehavior    always         collectionView register UICollectionViewCell self  forCellWithReuseIdentifier   Cell              override func viewWillLayoutSubviews             guard let collectionView   collectionView  let flowLayout   collectionView collectionViewLayout as  UICollectionViewFlowLayout else   return           let marginsAndInsets   flowLayout sectionInset left   flowLayout sectionInset right   collectionView safeAreaInsets left   collectionView safeAreaInsets right   flowLayout minimumInteritemSpacing   CGFloat cellsPerRow - 1          let itemWidth     collectionView bounds size width - marginsAndInsets    CGFloat cellsPerRow   rounded  down          flowLayout itemSize    CGSize width  itemWidth  height  itemWidth             override func collectionView   collectionView  UICollectionView  numberOfItemsInSection section  Int  - gt  Int           return 59            override func collectionView   collectionView  UICollectionView  cellForItemAt indexPath  IndexPath  - gt  UICollectionViewCell           let cell   collectionView dequeueReusableCell withReuseIdentifier   Cell   for  indexPath          cell backgroundColor   UIColor orange         return cell            override func viewWillTransition to size  CGSize  with coordinator  UIViewControllerTransitionCoordinator            collectionView  collectionViewLayout invalidateLayout           super viewWillTransition to  size  with  coordinator                3  Using UICollectionViewDelegateFlowLayout s collectionView   layout sizeForItemAt   method  import UIKit  class CollectionViewController  UICollectionViewController  UICollectionViewDelegateFlowLayout        let inset  CGFloat   10     let minimumLineSpacing  CGFloat   10     let minimumInteritemSpacing  CGFloat   10     let cellsPerRow   5      override func viewDidLoad             super viewDidLoad            collectionView  contentInsetAdjustmentBehavior    always         collectionView  register UICollectionViewCell self  forCellWithReuseIdentifier   Cell              func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  insetForSectionAt section  Int  - gt  UIEdgeInsets           return UIEdgeInsets top  inset  left  inset  bottom  inset  right  inset             func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  minimumLineSpacingForSectionAt section  Int  - gt  CGFloat           return minimumLineSpacing            func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  minimumInteritemSpacingForSectionAt section  Int  - gt  CGFloat           return minimumInteritemSpacing            func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  sizeForItemAt indexPath  IndexPath  - gt  CGSize           let marginsAndInsets   inset   2   collectionView safeAreaInsets left   collectionView safeAreaInsets right   minimumInteritemSpacing   CGFloat cellsPerRow - 1          let itemWidth     collectionView bounds size width - marginsAndInsets    CGFloat cellsPerRow   rounded  down          return CGSize width  itemWidth  height  itemWidth             override func collectionView   collectionView  UICollectionView  numberOfItemsInSection section  Int  - gt  Int           return 59            override func collectionView   collectionView  UICollectionView  cellForItemAt indexPath  IndexPath  - gt  UICollectionViewCell           let cell   collectionView dequeueReusableCell withReuseIdentifier   Cell   for  indexPath          cell backgroundColor   UIColor orange         return cell            override func viewWillTransition to size  CGSize  with coordinator  UIViewControllerTransitionCoordinator            collectionView  collectionViewLayout invalidateLayout           super viewWillTransition to  size  with  coordinator                4  Subclassing UICollectionViewFlowLayout and using UICollectionViewFlowLayout s estimatedItemSize property  CollectionViewController swift   import UIKit  class CollectionViewController  UICollectionViewController        let items              Lorem ipsum dolor sit amet  consectetur adipiscing elit             Lorem ipsum dolor sit amet  consectetur             Lorem ipsum dolor sit amet             Lorem ipsum dolor sit amet  consectetur             Lorem ipsum dolor sit amet  consectetur adipiscing             Lorem ipsum             Lorem ipsum dolor sit amet             Lorem ipsum dolor sit             Lorem ipsum dolor sit amet  consectetur adipiscing             Lorem ipsum dolor sit amet  consectetur adipiscing elit             Lorem ipsum dolor sit amet  consectetur adipiscing elit  sed do eiusmod tempor             Lorem ipsum dolor sit amet  consectetur              let columnLayout   FlowLayout          cellsPerRow  3          minimumInteritemSpacing  10          minimumLineSpacing  10          sectionInset  UIEdgeInsets top  10  left  10  bottom  10  right  10             override func viewDidLoad             super viewDidLoad            collectionView  collectionViewLayout   columnLayout         collectionView  contentInsetAdjustmentBehavior    always         collectionView  register Cell self  forCellWithReuseIdentifier   Cell              override func collectionView   collectionView  UICollectionView  numberOfItemsInSection section  Int  - gt  Int           return items count            override func collectionView   collectionView  UICollectionView  cellForItemAt indexPath  IndexPath  - gt  UICollectionViewCell           let cell   collectionView dequeueReusableCell withReuseIdentifier   Cell   for  indexPath  as  Cell         cell label text   items indexPath row          return cell            override func viewWillTransition to size  CGSize  with coordinator  UIViewControllerTransitionCoordinator            collectionView  collectionViewLayout invalidateLayout           super viewWillTransition to  size  with  coordinator             FlowLayout swift   import UIKit  class FlowLayout  UICollectionViewFlowLayout        let cellsPerRow  Int      required init cellsPerRow  Int   1  minimumInteritemSpacing  CGFloat   0  minimumLineSpacing  CGFloat   0  sectionInset  UIEdgeInsets    zero            self cellsPerRow   cellsPerRow          super init            self minimumInteritemSpacing   minimumInteritemSpacing         self minimumLineSpacing   minimumLineSpacing         self sectionInset   sectionInset         estimatedItemSize   UICollectionViewFlowLayout automaticSize            required init  coder aDecoder  NSCoder            fatalError  init coder   has not been implemented              override func layoutAttributesForItem at indexPath  IndexPath  - gt  UICollectionViewLayoutAttributes            guard let layoutAttributes   super layoutAttributesForItem at  indexPath  else   return nil           guard let collectionView   collectionView else   return layoutAttributes            let marginsAndInsets   collectionView safeAreaInsets left   collectionView safeAreaInsets right   sectionInset left   sectionInset right   minimumInteritemSpacing   CGFloat cellsPerRow - 1          layoutAttributes bounds size width     collectionView bounds width - marginsAndInsets    CGFloat cellsPerRow   rounded  down           return layoutAttributes            override func layoutAttributesForElements in rect  CGRect  - gt   UICollectionViewLayoutAttributes             let superLayoutAttributes   super layoutAttributesForElements in  rect   map    0 copy   as  UICollectionViewLayoutAttributes           guard scrollDirection     vertical else   return superLayoutAttributes            let layoutAttributes   superLayoutAttributes compactMap   layoutAttribute in             return layoutAttribute representedElementCategory     cell   layoutAttributesForItem at  layoutAttribute indexPath    layoutAttribute                        optional  Uncomment to top align cells that are on the same line                    let cellAttributes   layoutAttributes filter    0 representedElementCategory     cell            for     attributes  in Dictionary grouping  cellAttributes  by      0 center y   10  rounded  up    10                  guard let max   attributes max by     0 size height  lt   1 size height    else   continue               for attribute in attributes where attribute size height    max size height                   attribute frame origin y   max frame origin y                                                  optional  Uncomment to bottom align cells that are on the same line                    let cellAttributes   layoutAttributes filter    0 representedElementCategory     cell            for     attributes  in Dictionary grouping  cellAttributes  by      0 center y   10  rounded  up    10                  guard let max   attributes max by     0 size height  lt   1 size height    else   continue               for attribute in attributes where attribute size height    max size height                   attribute frame origin y    max frame maxY - attribute frame maxY                                              return layoutAttributes            Cell swift   import UIKit  class Cell  UICollectionViewCell        let label   UILabel        override init frame  CGRect            super init frame  frame           label numberOfLines   0         backgroundColor    orange         contentView addSubview label           label translatesAutoresizingMaskIntoConstraints   false         label topAnchor constraint equalTo  contentView layoutMarginsGuide topAnchor  isActive   true         label leadingAnchor constraint equalTo  contentView layoutMarginsGuide leadingAnchor  isActive   true         label trailingAnchor constraint equalTo  contentView layoutMarginsGuide trailingAnchor  isActive   true         label bottomAnchor constraint equalTo  contentView layoutMarginsGuide bottomAnchor  isActive   true            required init  coder aDecoder  NSCoder            fatalError  init coder   has not been implemented              override func preferredLayoutAttributesFitting   layoutAttributes  UICollectionViewLayoutAttributes  - gt  UICollectionViewLayoutAttributes           layoutIfNeeded           label preferredMaxLayoutWidth   label bounds size width         layoutAttributes bounds size height   contentView systemLayoutSizeFitting UIView layoutFittingCompressedSize  height         return layoutAttributes               Alternative implementation            override func preferredLayoutAttributesFitting   layoutAttributes  UICollectionViewLayoutAttributes  - gt  UICollectionViewLayoutAttributes           label preferredMaxLayoutWidth   layoutAttributes size width - contentView layoutMargins left - contentView layoutMargins right         layoutAttributes bounds size height   contentView systemLayoutSizeFitting UIView layoutFittingCompressedSize  height         return layoutAttributes

User · Answer

Swift 3 0  Works for both horizontal and vertical scroll directions and variable spacing  Specify number of columns  let numberOfColumns  CGFloat   3   Configure flowLayout to render specified numberOfColumns  if let flowLayout   collectionView  collectionViewLayout as  UICollectionViewFlowLayout       let horizontalSpacing   flowLayout scrollDirection     vertical   flowLayout minimumInteritemSpacing   flowLayout minimumLineSpacing     let cellWidth    collectionView frame width - max 0  numberOfColumns - 1  horizontalSpacing  numberOfColumns     flowLayout itemSize   CGSize width  cellWidth  height  cellWidth

User · Answer

Because UICollectionView is so flexible  there are multiple ways you could change the number of columns  depending on the kind of layout you use   The UICollectionViewFlowLayout  which is probably what you re working with  doesn t specify a number of columns directly  because it depends on the view size orientation   The easiest way to change it would be to set the itemSize property and or minimumInteritemSpacing minimumLineSpacing

User · Answer

I made a collection layout   To make the separator visible  Set the background color of the collection view to gray  One row per section   Useage   let layout   GridCollectionViewLayout   layout cellHeight   50    if not set  cellHeight   Collection height numberOfSections layout cellWidth   50     if not set  cellWidth   Collection width numberOfItems inSection  collectionView collectionViewLayout   layout   Layout   import UIKit  class GridCollectionViewLayout  UICollectionViewLayout     var cellWidth   CGFloat   0 var cellHeight   CGFloat   0 var seperator  CGFloat   1  private var cache    UICollectionViewLayoutAttributes       override func prepare          guard let collectionView   self collectionView else           return            self cache removeAll              let numberOfSections   collectionView numberOfSections          if cellHeight  lt   0                       cellHeight    collectionView bounds height - seperator CGFloat numberOfSections-1   CGFloat numberOfSections                     for section in 0   lt collectionView numberOfSections                let numberOfItems   collectionView numberOfItems inSection  section               let cellWidth2   CGFloat             if cellWidth  lt   0                               cellWidth2    collectionView bounds width - seperator CGFloat numberOfItems-1   CGFloat numberOfItems                            else                               cellWidth2   cellWidth                             for row in 0   lt numberOfItems                     let indexPath   NSIndexPath row  row  section  section                   let attributes   UICollectionViewLayoutAttributes forCellWith  indexPath as IndexPath                  attributes frame   CGRect x   cellWidth2 seperator  CGFloat row                                             y   cellHeight seperator  CGFloat section                                             width  cellWidth2                                            height  cellHeight                     row temp append attributes                   self cache append attributes                              self itemAttributes append row temp                override var collectionViewContentSize  CGSize        guard let collectionView   collectionView else               return CGSize zero            if  collectionView numberOfSections  lt   0                return collectionView bounds size            let width CGFloat     if cellWidth  lt   0               width   collectionView bounds width           else               width   cellWidth CGFloat collectionView numberOfItems inSection  0              let numberOfSections   CGFloat collectionView numberOfSections      var height CGFloat   0     height    numberOfSections   cellHeight     height     numberOfSections - 1    seperator        return CGSize width  width  height  height     override func layoutAttributesForElements in rect  CGRect  - gt   UICollectionViewLayoutAttributes          var layoutAttributes    UICollectionViewLayoutAttributes         for attributes in cache           if attributes frame intersects rect                layoutAttributes append attributes                      return layoutAttributes    override func layoutAttributesForItem at indexPath  IndexPath  - gt  UICollectionViewLayoutAttributes        return cache indexPath item

User · Answer

the perfect solution is to  Using UICollectionViewDelegateFlowLayout  but you can easily so calculate the cell width and divided on the wanted number of columns you want   the tricky is to make the width with no fraction    UICollectionViewLayout  collectionViewLayout sizeForItemAtIndexPath  NSIndexPath   indexPath     CGFloat screenWidth   self view frame size width     CGFloat marginWidth    screenWidth - collectionView frame size width        CGFloat cellWith    collectionView frame size width - marginWidth   3     cellWith  floorf cellWith         CGSize retval   CGSizeMake cellWith cellWith       return retval

User · Answer

Here is the working code for Swift 3 or above  to have a two-columns layout   func collectionView   collectionView  UICollectionView                      layout collectionViewLayout  UICollectionViewLayout                      sizeForItemAt indexPath  IndexPath  - gt  CGSize            let nbCol   2          let flowLayout   collectionViewLayout as  UICollectionViewFlowLayout     let totalSpace   flowLayout sectionInset left           flowLayout sectionInset right            flowLayout minimumInteritemSpacing   CGFloat nbCol - 1       let size   Int  collectionView bounds width - totalSpace    CGFloat nbCol       return CGSize width  size  height  size     Feel free to change  quot nbCol quot  to your desired number of columns

User · Answer

If you are lazy using delegate    extension UICollectionView       func setItemsInRow items  Int            if let layout   self collectionViewLayout as  UICollectionViewFlowLayout               let contentInset   self contentInset             let itemsInRow  CGFloat   CGFloat items               let innerSpace   layout minimumInteritemSpacing    itemsInRow - 1 0              let insetSpace   contentInset left   contentInset right   layout sectionInset left   layout sectionInset right             let width   floor  CGRectGetWidth frame  - insetSpace - innerSpace    itemsInRow               layout itemSize   CGSizeMake width  width                      PS  Should be called after rotation too

User · Answer

Expanding on noob s answer   func collectionView collectionView  UICollectionView      layout collectionViewLayout  UICollectionViewLayout      sizeForItemAtIndexPath indexPath  NSIndexPath  - gt  CGSize            let flowLayout   collectionViewLayout as  UICollectionViewFlowLayout         let totalSpace   flowLayout sectionInset left               flowLayout sectionInset right                flowLayout minimumInteritemSpacing   CGFloat numberOfItemsPerRow - 1           let size   Int  collectionView bounds width - totalSpace    CGFloat numberOfItemsPerRow           return CGSize width  size  height  size      This allows for any spacing between the cells  It assumes an Int member variable called numberOfItemsPerRow and also that all the cells are square and the same size   As noted in jhilgert00 s answer we must also react to orientation changes  but now by using viewWillTransitionToSize as willRotateToInterfaceOrientation is depreciated

User · Answer

I implemented UICollectionViewDelegateFlowLayout on my UICollectionViewController and override the method responsible for determining the size of the Cell  I then took the screen width and divided it with my column requirement  For example  I wanted to have 3 columns on each screen size  So here s what my code looks like -   -  CGSize collectionView  UICollectionView   collectionView                   layout  UICollectionViewLayout   collectionViewLayout   sizeForItemAtIndexPath  NSIndexPath   indexPath       CGRect screenRect     UIScreen mainScreen  bounds       CGFloat screenWidth   screenRect size width      float cellWidth   screenWidth   3 0    Replace the divisor with the column count requirement  Make sure to have it in float      CGSize size   CGSizeMake cellWidth  cellWidth        return size

User · Answer

Try This It s working perfect for me   Follow below steps   1  Define values in  h file         define kNoOfColumsForCollection 3       define kNoOfRowsForCollection 4       define kcellSpace 5       define kCollectionViewCellWidth  self view frame size width - kcellSpace kNoOfColumsForCollection  kNoOfColumsForCollection       define kCollectionViewCellHieght  self view frame size height-40- kcellSpace kNoOfRowsForCollection  kNoOfRowsForCollection   OR     define kNoOfColumsForCollection 3    define kCollectionViewCellWidthHieght  self view frame size width - 6 kNoOfColumsForCollection  kNoOfColumsForCollection   2 Add Code in collection View Layout data source methods as below     pragma mark Collection View Layout data source methods    collection view with autolayout  -  CGFloat collectionView  UICollectionView   collectionView layout  UICollectionViewLayout  collectionViewLayout minimumLineSpacingForSectionAtIndex  NSInteger section   return 4     -  CGFloat collectionView  UICollectionView   collectionView layout  UICollectionViewLayout  collectionViewLayout minimumInteritemSpacingForSectionAtIndex  NSInteger section     return 1     -  UIEdgeInsets collectionView  UICollectionView   collectionView layout  UICollectionViewLayout  collectionViewLayout insetForSectionAtIndex  NSInteger section   return UIEdgeInsetsMake 4  4  4  4     -  CGSize collectionView  UICollectionView   collectionView               layout  UICollectionViewLayout   collectionViewLayout    sizeForItemAtIndexPath  NSIndexPath   indexPath    return   CGSizeMake kCollectionViewCellWidth kCollectionViewCellHieght       CGSizeMake  kCollectionViewCellWidthHieght kCollectionViewCellWidthHieght       Hope this will be help for some one

User · Answer

I just wanted to append to Imanou Petit s answer  2   To ensure margins are exact regardless of screen width  I use an iterative solver with a desired margin  and the   of columns as inputs   I also added a directional flag on where their final margins will be compared to their target   The iterative solver is shown below and returns cellWidth and margin   private func iterativeCellSpacing targetMargins   CGFloat                                    cellsPerRow   Int                                    isMinTarget   Bool  - gt   CGFloat  CGFloat        var w   CGFloat   0     var m   CGFloat   targetMargins     let cols   CGFloat   CGFloat cellsPerRow       let numMargins   CGFloat   cols   1 0     let screenWidth   CGFloat   collectionView  bounds size width       var delta   CGFloat greatestFiniteMagnitude     while abs delta   gt  0 001               let totalMarginSpacing   numMargins   m         let totalCellSpacing   screenWidth - totalMarginSpacing          if  isMinTarget                        w   floor totalCellSpacing   cols              m   ceil  screenWidth - cols   w    numMargins                    else                       w   ceil totalCellSpacing   cols              m   floor  screenWidth - cols   w    numMargins                     delta   screenWidth - w   CGFloat cellsPerRow  - m   numMargins            return  w  m      I call it as such   fileprivate var margin  CGFloat   20 fileprivate var cellWidth   CGFloat   80 fileprivate let cellsPerRow   4  override func viewDidLoad         super viewDidLoad         cellWidth  margin    iterativeCellSpacing targetMargins  margin  cellsPerRow  4  isMinTarget  true              I then apply the cellWidth and margin values to the flow layout as such   extension MyCollectionController   UICollectionViewDelegateFlowLayout         func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  sizeForItemAt indexPath  IndexPath  -  CGSize               return CGSize width  cellWidth  height  cellWidth         override func viewWillTransition to size  CGSize  with coordinator  UIViewControllerTransitionCoordinator        collectionView  collectionViewLayout invalidateLayout       super viewWillTransition to  size  with  coordinator     func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  insetForSectionAt section  Int  - gt  UIEdgeInsets       return UIEdgeInsetsMake margin  margin  margin  margin     func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  minimumLineSpacingForSectionAt section  Int  - gt  CGFloat       return margin    func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  minimumInteritemSpacingForSectionAt section  Int  - gt  CGFloat       return margin        Hope this helps   There probably is an easier way to ensure margins are exact  but this is one method   Also  this code hasn t been tested for devices that allow rotating collectionviews   Thanks

[ios] UICollectionView Set number of columns

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