UICollectionView - dynamic cell height

Question

I need to display a bunch of collectionViewCells that have different heights  the views are too complex and I don t want to manually calculate the expected height  I want to enforce auto-layout to calculate cell height Calling dequeueReusableCellWithReuseIdentifier outside of cellForItemAtIndexPath breaks collectionView and causes it to crash Another problem is the cell is not in a separate xib  so I can t manually instantiate a temporary one and use it for height calculation  Any solutions for this  public func collectionView collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  sizeForItemAtIndexPath indexPath  NSIndexPath  - gt  CGSize            var cell   collectionView dequeueReusableCellWithReuseIdentifier cellIdentifier  forIndexPath  indexPath  as UICollectionViewCell     configureCell cell  item  items indexPath row            cell contentView setNeedsLayout       cell contentView layoutIfNeeded            return cell contentView systemLayoutSizeFittingSize UILayoutFittingCompressedSize     EDIT  Crash happens as soon as dequeueReusableCellWithReuseIdentifier is called  If I don t call that method and instead return a size everything works great and cells show up without the calculated size negative or zero sizes are not supported in the flow layout 2015-01-26 18 24 34 231  13383 9752256      Terminating app due to uncaught exception  NSRangeException   reason       -   NSArrayM objectAtIndex    index 1 beyond bounds  0    0       First throw call stack        0   CoreFoundation                      0x00000001095aef35   exceptionPreprocess   165     1   libobjc A dylib                     0x0000000109243bb7 objc exception throw   45     2   CoreFoundation                      0x0000000109499f33 -   NSArrayM objectAtIndex     227     3   UIKit                               0x0000000107419d9c - UICollectionViewFlowLayout  getSizingInfos    842     4   UIKit                               0x000000010741aca9 - UICollectionViewFlowLayout  fetchItemsInfoForRect     526     5   UIKit                               0x000000010741651f - UICollectionViewFlowLayout prepareLayout    257     6   UIKit                               0x000000010742da10 - UICollectionViewData  prepareToLoadData    67     7   UIKit                               0x00000001074301c6 - UICollectionViewData layoutAttributesForItemAtIndexPath     44     8   UIKit                               0x00000001073fddb1 - UICollectionView  dequeueReusableViewOfKind withIdentifier forIndexPath viewCategory     248     9                                       0x00000001042b824c  TFC1228BasePaginatingViewController14collectionViewfS0 FTCSo16UICollectionView6layoutCSo22UICollectionViewLayout22sizeForItemAtIndexPathCSo11NSIndexPath VSC6CGSize   700     10                                     0x00000001042b83d4  TToFC1228BasePaginatingViewController14collectionViewfS0 FTCSo16UICollectionView6layoutCSo22UICollectionViewLayout22sizeForItemAtIndexPathCSo11NSIndexPath VSC6CGSize   100     11  UIKit                               0x0000000107419e2e - UICollectionViewFlowLayout  getSizingInfos    988     12  UIKit                               0x000000010741aca9 - UICollectionViewFlowLayout  fetchItemsInfoForRect     526     13  UIKit                               0x000000010741651f - UICollectionViewFlowLayout prepareLayout    257     14  UIKit                               0x000000010742da10 - UICollectionViewData  prepareToLoadData    67     15  UIKit                               0x000000010742e0e9 - UICollectionViewData validateLayoutInRect     54     16  UIKit                               0x00000001073f67b8 - UICollectionView layoutSubviews    170     17  UIKit                               0x0000000106e3c973 - UIView CALayerDelegate  layoutSublayersOfLayer     521     18  QuartzCore                          0x0000000106b0fde8 - CALayer layoutSublayers    150     19  QuartzCore                          0x0000000106b04a0e  ZN2CA5Layer16layout if neededEPNS 11TransactionE   380     20  QuartzCore                          0x0000000106b0487e  ZN2CA5Layer28layout and display if neededEPNS 11TransactionE   24     21  QuartzCore                          0x0000000106a7263e  ZN2CA7Context18commit transactionEPNS 11TransactionE   242     22  QuartzCore                          0x0000000106a7374a  ZN2CA11Transaction6commitEv   390     23  QuartzCore                          0x0000000106a73db5  ZN2CA11Transaction17observer callbackEP19  CFRunLoopObservermPv   89     24  CoreFoundation                      0x00000001094e3dc7   CFRUNLOOP IS CALLING OUT TO AN OBSERVER CALLBACK FUNCTION     23     25  CoreFoundation                      0x00000001094e3d20   CFRunLoopDoObservers   368     26  CoreFoundation                      0x00000001094d9b53   CFRunLoopRun   1123     27  CoreFoundation                      0x00000001094d9486 CFRunLoopRunSpecific   470     28  GraphicsServices                    0x000000010be869f0 GSEventRunModal   161     29  UIKit                               0x0000000106dc3420 UIApplicationMain   1282     30                                      0x000000010435c709 main   169     31  libdyld dylib                       0x000000010a0f2145 start   1   libc  abi dylib  terminating with uncaught exception of type NSException

User · Answer

I just ran into this problem on a UICollectionView and the way that i solved it similar to the answer above but in a pure UICollectionView way.

Create a custom UICollectionViewCell that contains whatever you will be filling it with to make it dynamic. I created its own .xib for it as it seems like the easiest approach.
Add constraints in that .xib that allow for the cell to be calculated from top to bottom. The re-sizing won't work if you haven't accounted for all of the height. Say you have a view on top, then a label underneath it, and another label underneath that. You would need to connect constraints to the top of the cell to the top of that view, then the bottom of the view to the top of the first label, bottom of first label to the top of the second label, and bottom of second label to bottom of cell.

Load the .xib into the viewcontroller and register it with the collectionView on viewDidLoad

let nib = UINib(nibName: CustomCellName, bundle: nil)
self.collectionView!.registerNib(nib, forCellWithReuseIdentifier: "customCellID")`

Load a second copy of that xib into the class and store it as a property so you can use it to determine the size of what that cell should be

let sizingNibNew = NSBundle.mainBundle().loadNibNamed(CustomCellName, owner: CustomCellName.self, options: nil) as NSArray
self.sizingNibNew = (sizingNibNew.objectAtIndex(0) as? CustomViewCell)!

Implement the UICollectionViewFlowLayoutDelegate in your view controller. The method that matters is called sizeForItemAtIndexPath. Inside that method you will need to pull the data from the datasource that is associated with that cell from the indexPath. Then configure the sizingCell and call preferredLayoutSizeFittingSize. The method returns a CGSize which will consist of the width minus the content insets and the height that is returned from self.sizingCell.preferredLayoutSizeFittingSize(targetSize).

override func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
    guard let data = datasourceArray?[indexPath.item] else {
        return CGSizeZero
    }
    let sectionInset = self.collectionView?.collectionViewLayout.sectionInset
    let widthToSubtract = sectionInset!.left + sectionInset!.right

    let requiredWidth = collectionView.bounds.size.width


    let targetSize = CGSize(width: requiredWidth, height: 0)

    sizingNibNew.configureCell(data as! CustomCellData, delegate: self)
    let adequateSize = self.sizingNibNew.preferredLayoutSizeFittingSize(targetSize)
    return CGSize(width: (self.collectionView?.bounds.width)! - widthToSubtract, height: adequateSize.height)
 }

In the class of the custom cell itself you will need to override awakeFromNib and tell the contentView that its size needs to be flexible

 override func awakeFromNib() {
    super.awakeFromNib()
    self.contentView.autoresizingMask = [UIViewAutoresizing.FlexibleHeight]
 }

In the custom cell override layoutSubviews

 override func layoutSubviews() {
   self.layoutIfNeeded()
  }

In the class of the custom cell implement preferredLayoutSizeFittingSize. This is where you will need to do any trickery on the items that are being laid out. If its a label you will need to tell it what its preferredMaxWidth should be.

func preferredLayoutSizeFittingSize(_ targetSize: CGSize)-> CGSize {

    let originalFrame = self.frame
    let originalPreferredMaxLayoutWidth = self.label.preferredMaxLayoutWidth


    var frame = self.frame
    frame.size = targetSize
    self.frame = frame

    self.setNeedsLayout()
    self.layoutIfNeeded()
    self.label.preferredMaxLayoutWidth = self.questionLabel.bounds.size.width


    // calling this tells the cell to figure out a size for it based on the current items set
    let computedSize = self.systemLayoutSizeFittingSize(UILayoutFittingCompressedSize)

    let newSize = CGSize(width:targetSize.width, height:computedSize.height)

    self.frame = originalFrame
    self.questionLabel.preferredMaxLayoutWidth = originalPreferredMaxLayoutWidth

    return newSize
}

All those steps should give you the correct sizes. If your getting 0 or other funky numbers than you haven't set up your constraints properly.

User · Answer

I followed the steps mentioned in this SO and everything is fine except when my Collection View has less data  text  to make it wide enough   Checking the documentation in systemLyaoutSizeFittingSize  I have this solution so my cell take up the width as I requested   -  CGSize calculateSizeForSizingCell  UICollectionViewCell   sizingCell width  CGFloat width       CGRect frame   sizingCell frame      frame size width   width      sizingCell frame   frame       sizingCell setNeedsLayout        sizingCell layoutIfNeeded        CGSize size    sizingCell systemLayoutSizeFittingSize UILayoutFittingCompressedSize                         withHorizontalFittingPriority UILayoutPriorityRequired                               verticalFittingPriority UILayoutPriorityFittingSizeLevel       return size      Hope this would help someone   -  CGSize systemLayoutSizeFittingSize  CGSize targetSize NS AVAILABLE IOS 6 0     Apple doc      Equivalent to sending -systemLayoutSizeFittingSize withHorizontalFittingPriority verticalFittingPriority  with UILayoutPriorityFittingSizeLevel for both priorities    While the default value is  pretty low  according to Apple s doc      When you send - UIView systemLayoutSizeFittingSize    the size fitting most closely to the target size  the argument  is computed   UILayoutPriorityFittingSizeLevel is the priority level with which the view wants to conform to the target size in that computation   It s quite low   It is generally not appropriate to make a constraint at exactly this priority   You want to be higher or lower    So my change of default behavior is to enforce the width  horizontal fitting  with UILayoutPriorityRequired

User · Answer

We can maintain dynamic height for collection view cell without xib only using storyboard    -  CGSize collectionView  UICollectionView   collectionView                   layout  UICollectionViewLayout  collectionViewLayout   sizeForItemAtIndexPath  NSIndexPath   indexPath            NSAttributedString  labelString     NSAttributedString alloc  initWithString   Your long string goes here  attributes   NSFontAttributeName  UIFont systemFontOfSize 17 0             CGRect cellRect    labelString boundingRectWithSize CGSizeMake cellWidth  MAXFLOAT  options NSStringDrawingUsesLineFragmentOrigin context nil            return CGSizeMake cellWidth  cellRect size height       Make sure that numberOfLines in IB should be 0

User · Answer

Follow bolnad answer up to Step 4   Then make it simpler by replacing all the other steps with   func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  sizeForItemAt indexPath  IndexPath  - gt  CGSize           Configure your cell     sizingNibNew configureCell data as  CustomCellData  delegate  self          We use the full width minus insets     let width   collectionView frame size width - collectionView sectionInset left - collectionView sectionInset right         Constrain our cell to this width      let height   sizingNibNew systemLayoutSizeFitting CGSize width  width  height   infinity   withHorizontalFittingPriority  UILayoutPriorityRequired  verticalFittingPriority  UILayoutPriorityFittingSizeLevel  height      return CGSize width  width  height  height

User · Answer

Here is a Ray Wenderlich tutorial that shows you how to use AutoLayout to dynamically size UITableViewCells  I would think it would be the same for UICollectionViewCell    Basically  though  you end up dequeueing and configuring a prototype cell and grabbing its height  After reading this article  I decided to NOT implement this method and just write some clear  explicit sizing code   Here s what I consider the  secret sauce  for the entire article   -  CGFloat tableView  UITableView   tableView heightForRowAtIndexPath  NSIndexPath   indexPath       return  self heightForBasicCellAtIndexPath indexPath      -  CGFloat heightForBasicCellAtIndexPath  NSIndexPath   indexPath       static RWBasicCell  sizingCell   nil      static dispatch once t onceToken      dispatch once  amp onceToken             sizingCell    self tableView dequeueReusableCellWithIdentifier RWBasicCellIdentifier                 self configureBasicCell sizingCell atIndexPath indexPath       return  self calculateHeightForConfiguredSizingCell sizingCell      -  CGFloat calculateHeightForConfiguredSizingCell  UITableViewCell   sizingCell        sizingCell setNeedsLayout        sizingCell layoutIfNeeded        CGSize size    sizingCell contentView systemLayoutSizeFittingSize UILayoutFittingCompressedSize       return size height   1 0f     Add 1 0f for the cell separator height      EDIT  I did some research into your crash and decided that there is no way to get this done without a custom XIB  While that is a bit frustrating  you should be able to cut and paste from your Storyboard to a custom  empty XIB   Once you ve done that  code like the following will get you going       ViewController m  import  ViewController h   import  CollectionViewCell h   interface ViewController     lt UICollectionViewDataSource  UICollectionViewDelegate  UICollectionViewDelegateFlowLayout gt        property  weak  nonatomic  IBOutlet CollectionViewCell  cell   property  weak  nonatomic  IBOutlet UICollectionView    collectionView   end  implementation ViewController -  void viewDidLoad        super viewDidLoad       self view backgroundColor    UIColor lightGrayColor        self collectionView registerNib  UINib nibWithNibName   CollectionViewCell  bundle nil  forCellWithReuseIdentifier   cell      -  void viewDidAppear  BOOL animated        super viewDidAppear animated       NSLog   viewDidAppear         -  NSInteger numberOfSectionsInCollectionView  UICollectionView   collectionView       return 1    -  NSInteger collectionView  UICollectionView   collectionView numberOfItemsInSection  NSInteger section       return 50    -  CGFloat collectionView  UICollectionView   collectionView layout  UICollectionViewLayout   collectionViewLayout minimumInteritemSpacingForSectionAtIndex  NSInteger section       return 10 0f    -  CGFloat collectionView  UICollectionView   collectionView layout  UICollectionViewLayout   collectionViewLayout minimumLineSpacingForSectionAtIndex  NSInteger section       return 10 0f    -  CGSize collectionView  UICollectionView   collectionView layout  UICollectionViewLayout   collectionViewLayout sizeForItemAtIndexPath  NSIndexPath   indexPath       return  self sizingForRowAtIndexPath indexPath     -  CGSize sizingForRowAtIndexPath  NSIndexPath   indexPath       static NSString  title                      This is a long title that will cause some wrapping to occur  This is a long title that will cause some wrapping to occur        static NSString  subtitle                   This is a long subtitle that will cause some wrapping to occur  This is a long subtitle that will cause some wrapping to occur        static NSString  buttonTitle                This is a really long button title that will cause some wrapping to occur        static CollectionViewCell  sizingCell     nil      static dispatch once t onceToken      dispatch once  amp onceToken             sizingCell                              NSBundle mainBundle  loadNibNamed   CollectionViewCell  owner self options nil  0                sizingCell configureWithTitle title subtitle  NSString stringWithFormat       Number  d    subtitle   int indexPath row  buttonTitle buttonTitle        sizingCell setNeedsLayout        sizingCell layoutIfNeeded       CGSize cellSize    sizingCell contentView systemLayoutSizeFittingSize UILayoutFittingCompressedSize       NSLog   cellSize       NSStringFromCGSize cellSize        return cellSize    -  UICollectionViewCell   collectionView  UICollectionView   collectionView cellForItemAtIndexPath  NSIndexPath   indexPath       static NSString  title                      This is a long title that will cause some wrapping to occur  This is a long title that will cause some wrapping to occur        static NSString  subtitle                   This is a long subtitle that will cause some wrapping to occur  This is a long subtitle that will cause some wrapping to occur        static NSString  buttonTitle                This is a really long button title that will cause some wrapping to occur        CollectionViewCell  cell                   collectionView dequeueReusableCellWithReuseIdentifier   cell  forIndexPath indexPath        cell configureWithTitle title subtitle  NSString stringWithFormat       Number  d    subtitle   int indexPath row  buttonTitle buttonTitle       return cell     end   The code above  along with a very basic UICollectionViewCell subclass and associated XIB  gives me this

User · Answer

Swift 4    I have created a Xib for UICollectionViewCell which seems to be the good approach   extension ViewController  UICollectionViewDelegateFlowLayout        func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  sizeForItemAt indexPath  IndexPath  - gt  CGSize           return size indexPath  indexPath             private func size for indexPath  IndexPath  - gt  CGSize              load cell from Xib         let cell   Bundle main loadNibNamed  ACollectionViewCell   owner  self  options  nil   first as  ACollectionViewCell             configure cell with data in it         let data   self data indexPath item          cell configure withData  data           cell setNeedsLayout           cell layoutIfNeeded               width that you want         let width   collectionView frame width         let height  CGFloat   0          let targetSize   CGSize width  width  height  height              get size with width that you want and automatic height         let size   cell contentView systemLayoutSizeFitting targetSize  withHorizontalFittingPriority   defaultHigh  verticalFittingPriority   fittingSizeLevel             if you want height and width both to be dynamic use below            let size   cell contentView systemLayoutSizeFitting UILayoutFittingCompressedSize           return size            note  I don t recommend setting image when configuring data in this size determining case  It gave me the distorted unwanted result  Configuring texts only gave me below result

User · Answer

Swift 4 answer based on helpful answer from  mbm29414   Unfortunately  it requires the use of a XIB file  There doesn t appear to be an alternative   The key parts are using a sizing cell  created only once  and registering the XIB when initializing the collection view   Then you size each cell dynamically within the sizeForItemAt function      UICollectionView Vars and Constants let CellXIBName   YouViewCell XIBName let CellReuseID   YouViewCell ReuseID var sizingCell   YouViewCell     fileprivate func initCollectionView            Connect to view controller     collectionView dataSource   self     collectionView delegate   self         Register XIB     collectionView register UINib nibName  CellXIBName  bundle  nil   forCellWithReuseIdentifier  CellReuseID          Create sizing cell for dynamically sizing cells     sizingCell   Bundle main loadNibNamed CellXIBName  owner  self  options  nil   first as  YourViewCell         Set scroll direction     let layout   UICollectionViewFlowLayout       layout scrollDirection    vertical     collectionView collectionViewLayout   layout         Set properties     collectionView alwaysBounceVertical   true     collectionView alwaysBounceHorizontal   false         Set top bottom padding     collectionView contentInset   UIEdgeInsets top  collectionViewTopPadding  left  collectionViewSidePadding  bottom  collectionViewBottomPadding  right  collectionViewSidePadding          Hide scrollers     collectionView showsVerticalScrollIndicator   false     collectionView showsHorizontalScrollIndicator   false     func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  sizeForItemAt indexPath  IndexPath  - gt  CGSize          Get cell data and render post     let data   YourData indexPath row      sizingCell renderCell data  data          Get cell size     sizingCell setNeedsLayout       sizingCell layoutIfNeeded       let cellSize   sizingCell systemLayoutSizeFitting UIView layoutFittingCompressedSize          Return cell size     return cellSize

User · Answer

It worked for me  hope you too    Note  I have used auto layout in Nib  remember add top and bottom contraints for subviews in contentView  func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  sizeForItemAt indexPath  IndexPath  - gt  CGSize              let cell   YourCollectionViewCell instantiateFromNib              cell frame size width   collectionView frame width            cell data   viewModel data indexPath item             let resizing   cell systemLayoutSizeFitting UILayoutFittingCompressedSize  withHorizontalFittingPriority  UILayoutPriority required  verticalFittingPriority  UILayoutPriority fittingSizeLevel             return resizing

User · Answer

TL DR  Scan down to image  and then check out working project here   Updating my answer for a simpler solution that I found    In my case  I wanted to fix the width  and have variable height cells   I wanted a drop in  reusable solution that handled rotation and didn t require a lot of intervention   What I arrived at  was override  just  systemLayoutFitting      in the collection cell  in this case a base class for me   and first defeat UICollectionView s effort to set the wrong dimension on contentView by adding a constraint for the known dimension  in this case  the width   class EstimatedWidthCell  UICollectionViewCell       override init frame  CGRect            super init frame  frame          contentView translatesAutoresizingMaskIntoConstraints   false            required init  coder aDecoder  NSCoder            super init coder  aDecoder          contentView translatesAutoresizingMaskIntoConstraints   false            override func systemLayoutSizeFitting            targetSize  CGSize  withHorizontalFittingPriority         horizontalFittingPriority  UILayoutPriority          verticalFittingPriority  UILayoutPriority  - gt  CGSize            width constant   targetSize width   and then return the final size for the cell - used for  and this feels like a bug  the dimension of the cell itself  but not contentView - which is otherwise constrained to a conflicting size  hence the constraint above   To calculate the correct cell size  I use a lower priority for the dimension that I wanted to float  and I get back the height required to fit the content within the width to which I want to fix           let size   contentView systemLayoutSizeFitting              CGSize width  targetSize width  height  1               withHorizontalFittingPriority   required              verticalFittingPriority  verticalFittingPriority           print     function     line    targetSize  - gt    size            return size            lazy var width  NSLayoutConstraint             return contentView widthAnchor              constraint equalToConstant  bounds size width               isActive true              But where does this width come from  It is configured via the estimatedItemSize on the collection view s flow layout   lazy var collectionView  UICollectionView         let view   UICollectionView frame  CGRect    collectionViewLayout  layout      view backgroundColor    cyan     view translatesAutoresizingMaskIntoConstraints   false     return view      lazy var layout  UICollectionViewFlowLayout         let layout   UICollectionViewFlowLayout       let width   view bounds size width    should adjust for inset     layout estimatedItemSize   CGSize width  width  height  10      layout scrollDirection    vertical     return layout       Finally  to handle rotation  I implement trailCollectionDidChange to invalidate the layout   override func traitCollectionDidChange   previousTraitCollection  UITraitCollection         layout estimatedItemSize   CGSize width  view bounds size width  height  10      layout invalidateLayout       super traitCollectionDidChange previousTraitCollection      The final result looks like this     And I have published a working sample here

User · Answer

Seems like it s quite a popular question  so I will try to make my humble contribution     The code below is Swift 4 solution for no-storyboard setup  It utilizes some approaches from previous answers  therefore it prevents Auto Layout warning caused on device rotation    I am sorry if code samples are a bit long  I want to provide an  easy-to-use  solution fully hosted by StackOverflow  If you have any suggestions to the post -  please  share the idea and I will update it accordingly    The setup   Two classes  ViewController swift and MultilineLabelCell swift - Cell containing single UILabel    MultilineLabelCell swift  import UIKit  class MultilineLabelCell  UICollectionViewCell       static let reuseId    MultilineLabelCellReuseId       private let label  UILabel   UILabel frame   zero       override init frame  CGRect            super init frame  frame           layer borderColor   UIColor red cgColor         layer borderWidth   1 0          label numberOfLines   0         label lineBreakMode    byWordWrapping          let labelInset   UIEdgeInsets top  10  left  10  bottom  -10  right  -10          contentView addSubview label          label translatesAutoresizingMaskIntoConstraints   false         label topAnchor constraint equalTo  contentView layoutMarginsGuide topAnchor  constant  labelInset top  isActive   true         label leadingAnchor constraint equalTo  contentView layoutMarginsGuide leadingAnchor  constant  labelInset left  isActive   true         label trailingAnchor constraint equalTo  contentView layoutMarginsGuide trailingAnchor  constant  labelInset right  isActive   true         label bottomAnchor constraint equalTo  contentView layoutMarginsGuide bottomAnchor  constant  labelInset bottom  isActive   true          label layer borderColor   UIColor black cgColor         label layer borderWidth   1 0            required init  coder aDecoder  NSCoder            fatalError  Storyboards are quicker  easier  more seductive  Not stronger then Code               func configure text  String             label text   text            override func preferredLayoutAttributesFitting   layoutAttributes  UICollectionViewLayoutAttributes  - gt  UICollectionViewLayoutAttributes           label preferredMaxLayoutWidth   layoutAttributes size width - contentView layoutMargins left - contentView layoutMargins left         layoutAttributes bounds size height   systemLayoutSizeFitting UIView layoutFittingCompressedSize  height         return layoutAttributes           ViewController swift  import UIKit  let samuelQuotes          Samuel says         Add different length strings here for better testing     class ViewController  UIViewController  UICollectionViewDataSource  UICollectionViewDelegateFlowLayout       private set  var collectionView  UICollectionView         Initializers     init                Create new  UICollectionView  and set  UICollectionViewFlowLayout  as its layout         collectionView   UICollectionView frame   zero  collectionViewLayout  UICollectionViewFlowLayout            super init nibName  nil  bundle  nil             required init  coder aDecoder  NSCoder               Create new  UICollectionView  and set  UICollectionViewFlowLayout  as its layout         collectionView   UICollectionView frame   zero  collectionViewLayout  UICollectionViewFlowLayout            super init coder  aDecoder             override func viewDidLoad             super viewDidLoad            title    Dynamic size sample              Register Cells         collectionView register MultilineLabelCell self  forCellWithReuseIdentifier  MultilineLabelCell reuseId              Add  coolectionView  to display hierarchy and setup its appearance         view addSubview collectionView          collectionView backgroundColor    white         collectionView contentInsetAdjustmentBehavior    always         collectionView contentInset   UIEdgeInsets top  10  left  10  bottom  10  right  10              Setup Autolayout constraints         collectionView translatesAutoresizingMaskIntoConstraints   false         collectionView bottomAnchor constraint equalTo  view bottomAnchor  constant  0  isActive   true         collectionView leftAnchor constraint equalTo  view leftAnchor  constant  0  isActive   true         collectionView topAnchor constraint equalTo  view topAnchor  constant  0  isActive   true         collectionView rightAnchor constraint equalTo  view rightAnchor  constant  0  isActive   true             Setup  dataSource  and  delegate          collectionView dataSource   self         collectionView delegate   self           collectionView collectionViewLayout as  UICollectionViewFlowLayout  estimatedItemSize   UICollectionViewFlowLayout automaticSize          collectionView collectionViewLayout as  UICollectionViewFlowLayout  sectionInsetReference    fromLayoutMargins               MARK  - UICollectionViewDataSource -     func collectionView   collectionView  UICollectionView  cellForItemAt indexPath  IndexPath  - gt  UICollectionViewCell           let cell   collectionView dequeueReusableCell withReuseIdentifier  MultilineLabelCell reuseId  for  indexPath  as  MultilineLabelCell         cell configure text  samuelQuotes indexPath row           return cell            func collectionView   collectionView  UICollectionView  numberOfItemsInSection section  Int  - gt  Int           return samuelQuotes count               MARK  - UICollectionViewDelegateFlowLayout -     func collectionView   collectionView  UICollectionView  layout collectionViewLayout  UICollectionViewLayout  sizeForItemAt indexPath  IndexPath  - gt  CGSize           let sectionInset    collectionViewLayout as  UICollectionViewFlowLayout  sectionInset         let referenceHeight  CGFloat   100    Approximate height of your cell         let referenceWidth   collectionView safeAreaLayoutGuide layoutFrame width             - sectionInset left             - sectionInset right             - collectionView contentInset left             - collectionView contentInset right         return CGSize width  referenceWidth  height  referenceHeight            To run this sample create new Xcode project  create corresponding files and replace AppDelegate contents with the following code   import UIKit   UIApplicationMain class AppDelegate  UIResponder  UIApplicationDelegate        var window  UIWindow      var navigationController  UINavigationController       func application   application  UIApplication  didFinishLaunchingWithOptions launchOptions   UIApplication LaunchOptionsKey  Any    - gt  Bool           window   UIWindow frame  UIScreen main bounds           if let window   window               let vc   ViewController               navigationController   UINavigationController rootViewController  vc              window rootViewController   navigationController             window makeKeyAndVisible                      return true

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