UICollectionView - 动态单元格高度？ [复制]

Question

我需要显示一堆具有不同高度的 collectionViewCell。视图太复杂了，我不想手动计算预期的高度。我想强制执行自动布局来计算单元格高度

在cellForItemAtIndexPath 之外调用dequeueReusableCellWithReuseIdentifier 会破坏collectionView 并导致其崩溃

另一个问题是单元格不在单独的 xib 中，所以我不能手动实例化一个临时单元格并将其用于高度计算。

有什么解决办法吗？

public func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> 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)
}

编辑：

一旦调用dequeueReusableCellWithReuseIdentifier，就会发生崩溃。如果我不调用该方法而是返回一个大小，一切都会很好，并且单元格会在没有计算出的大小的情况下显示

流布局不支持负数或零大小

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

Answer 1

这是一个Ray Wenderlich tutorial，它向您展示了如何使用 AutoLayout 来动态调整UITableViewCells 的大小。我认为UICollectionViewCell 也是如此。

不过，基本上，您最终会出列并配置原型单元格并获取其高度。读完这篇文章后，我决定不实现这个方法，只写一些清晰、明确的大小调整代码。

这是我认为整篇文章的“秘诀”：

- (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(&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
}

---

编辑：我对您的崩溃进行了一些研究，并认为没有自定义 XIB 就无法完成此操作。虽然这有点令人沮丧，但您应该能够从 Storyboard 剪切和粘贴到自定义的空 XIB。

完成此操作后，以下代码将助您一臂之力：

//  ViewController.m
#import "ViewController.h"
#import "CollectionViewCell.h"
@interface ViewController () <UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout> {

}
@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(&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

上面的代码（连同一个非常基本的UICollectionViewCell 子类和相关的 XIB）给了我这个：

Answer 2

我刚刚在 UICollectionView 上遇到了这个问题，我解决它的方式类似于上面的答案，但是以纯 UICollectionView 的方式。

1. 创建一个自定义 UICollectionViewCell，其中包含您将要填充的任何内容以使其动态化。我为它创建了自己的 .xib，因为这似乎是最简单的方法。

2. 在该 .xib 中添加允许从上到下计算单元格的约束。如果您没有考虑所有高度，则重新调整大小将不起作用。假设您在顶部有一个视图，然后在其下方有一个标签，在其下方有另一个标签。您需要将约束连接到单元格的顶部到该视图的顶部，然后将视图的底部连接到第一个标签的顶部，第一个标签的底部到第二个标签的顶部，以及第二个标签的底部到单元格底部。

3. 将 .xib 加载到 viewcontroller 中，并将其注册到 viewDidLoad 上的 collectionView 中

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

4. 将该 xib 的第二个副本加载到类中并将其存储为属性，以便您可以使用它来确定该单元格的大小

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

5. 在您的视图控制器中实现UICollectionViewFlowLayoutDelegate。重要的方法称为sizeForItemAtIndexPath。在该方法中，您需要从 indexPath 中与该单元格关联的数据源中提取数据。然后配置 sizingCell 并调用preferredLayoutSizeFittingSize。该方法返回一个 CGSize，它将由宽度减去内容插入和从 self.sizingCell.preferredLayoutSizeFittingSize(targetSize) 返回的高度组成。

   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)
    }
   

6. 在自定义单元格本身的类中，您需要覆盖 awakeFromNib 并告诉 contentView 它的大小需要灵活

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

7. 在自定义单元格中覆盖layoutSubviews

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

8. 在自定义单元的类中实现preferredLayoutSizeFittingSize。这是您需要对正在布置的项目进行任何技巧的地方。如果它是一个标签，你需要告诉它它的preferredMaxWidth 应该是多少。

   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
   }
   

所有这些步骤都应该为您提供正确的尺寸。如果您得到 0 或其他时髦的数字，那么您没有正确设置约束。

Answer 3

我们可以在没有 xib 的情况下保持集合视图单元格的动态高度（仅使用故事板）。

- (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);
}

确保 IB 中的 numberOfLines 应为 0。

Answer 4

Swift 4.*

我为 UICollectionViewCell 创建了一个 Xib，这似乎是个好方法。

extension ViewController: UICollectionViewDelegateFlowLayout {

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

    private func size(for indexPath: IndexPath) -> 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：我不建议在这种大小确定的情况下配置数据时设置图像。它给了我扭曲/不想要的结果。配置文本只给了我以下结果。

Answer 5

TL;DR：向下扫描到图像，然后查看working project here.

更新我的答案以获得我找到的更简单的解决方案..

就我而言，我想固定宽度，并拥有可变高度的单元格。我想要一个可重复使用的解决方案，可以处理轮换并且不需要太多干预。

我到达的结果是在集合单元格中覆盖（只是）systemLayoutFitting(...)（在这种情况下是我的基类），并首先通过添加约束来击败 UICollectionView 在contentView 上设置错误维度的努力已知尺寸，在本例中为宽度。

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) -> CGSize {

        width.constant = targetSize.width

然后返回单元格的最终大小 - 用于（这感觉像一个错误）单元格本身的尺寸，但不是 contentView - 否则会被限制为冲突的大小（因此上面的约束） .为了计算正确的单元格大小，我对想要浮动的维度使用了较低的优先级，然后我得到了使内容适合我想要修复的宽度所需的高度：

        let size = contentView.systemLayoutSizeFitting(
            CGSize(width: targetSize.width, height: 1),
            withHorizontalFittingPriority: .required,
            verticalFittingPriority: verticalFittingPriority)

        print("\(#function) \(#line) \(targetSize) -> \(size)")
        return size
    }

    lazy var width: NSLayoutConstraint = {
        return contentView.widthAnchor
            .constraint(equalToConstant: bounds.size.width)
            .isActive(true)
    }()
}

但是这个宽度是从哪里来的呢？它是通过集合视图的流布局上的estimatedItemSize 配置的：

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
}()

最后，为了处理旋转，我实现了trailCollectionDidChange 使布局无效：

override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
    layout.estimatedItemSize = CGSize(width: view.bounds.size.width, height: 10)
    layout.invalidateLayout()
    super.traitCollectionDidChange(previousTraitCollection)
}

最终的结果是这样的：

我已经发布了a working sample here.

Answer 6

似乎这是一个很受欢迎的问题，所以我会尽力做出我的微薄贡献。

---

下面的代码是 Swift 4 无故事板设置的解决方案。它利用了以前答案中的一些方法，因此它可以防止在设备旋转时引起自动布局警告。

如果代码示例有点长，我很抱歉。我想提供一个完全由 StackOverflow 托管的“易于使用”的解决方案。如果您对帖子有任何建议 - 请分享这个想法，我会相应地更新它。

设置：

两个类：ViewController.swift 和 MultilineLabelCell.swift - 包含单个 UILabel 的单元格。

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) -> 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) -> 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) -> Int {
        return samuelQuotes.count
    }

    // MARK: - UICollectionViewDelegateFlowLayout -
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> 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)
    }
}

要运行此示例，请创建新的 Xcode 项目，创建相应的文件并将 AppDelegate 内容替换为以下代码：

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?
    var navigationController: UINavigationController?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> 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
    }
}

Answer 7

Swift 4 答案基于来自 @mbm29414 的有用答案。

不幸的是，它需要使用 XIB 文件。似乎没有其他选择。

关键部分是使用大小调整单元（仅创建一次）并在初始化集合视图时注册 XIB。

然后在sizeForItemAt 函数中动态调整每个单元格的大小。

// 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) -> 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
}

Answer 8

我按照此 SO 中提到的步骤进行操作，一切都很好，除非我的 Collection View 的数据（文本）较少以使其足够宽。检查systemLyaoutSizeFittingSize 中的文档，我有这个解决方案，所以我的单元格占用了我要求的宽度：

- (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;
}

希望这会对某人有所帮助。

- (CGSize)systemLayoutSizeFittingSize:(CGSize)targetSize NS_AVAILABLE_IOS(6_0);

苹果文档：

相当于发送 -systemLayoutSizeFittingSize:withHorizo​​ntalFittingPriority:verticalFittingPriority: with UILayoutPriorityFittingSizeLevel 两个优先级。

虽然根据 Apple 的文档，默认值为“相当低”：

当您发送 -[UIView systemLayoutSizeFittingSize:] 时，将计算最接近目标尺寸（参数）的尺寸。 UILayoutPriorityFittingSizeLevel 是视图希望在计算中符合目标大小的优先级。这是相当低的。在这个优先级上进行约束通常是不合适的。你想要更高或更低。

所以我对默认行为的更改是使用UILayoutPriorityRequired 强制宽度（水平拟合）。

Answer 9

按照 bolnad answer 直到第 4 步。

然后将所有其他步骤替换为：

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

Answer 10

它对我有用，希望你也一样。

*注意：我在 Nib 中使用过自动布局，记得在 contentView 中为子视图添加顶部和底部约束

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