Question

我需要显示一堆具有不同高度的collectionViewCell。视图太复杂，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dequeueReusableCellWithReuseIdentifier之外调用cellForItemAtIndexPath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，因此我无法手动实例化临时单元并将其用于高度计算。

任何解决方案吗？

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)
}

修改

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，一切都很好，单元格显示没有计算的大小

流程布局

不支持

负或零尺寸

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

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，但是采用纯粹的UICollectionView方式。

创建一个自定义UICollectionViewCell，其中包含您将填充它的任何内容以使其动态化。我为它创建了自己的.xib，因为它似乎是最简单的方法。
在.xib中添加约束，允许从上到下计算单元格。如果你没有考虑到所有的高度，重新调整大小将不起作用。假设您有一个顶部的视图，然后是一个标签，下面是另一个标签。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，将第一个标签的底部连接到第二个标签的顶部，以及第二个标签的底部到了细胞的底部。

将.xib加载到viewcontroller中并使用viewDidLoad上的collectionView注册它

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

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)!

在视图控制器中实现UICollectionViewFlowLayoutDelegate。重要的方法称为sizeForItemAtIndexPath。在该方法中，您需要从indexPath中提取与该单元格关联的数据源中的数据。然后配置sizingCell并调用preferredLayoutSizeFittingSize。该方法返回一个CGSize，它包含宽度减去内容插入和从self.sizingCell.preferredLayoutSizeFittingSize(targetSize)返回的高度。

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)
 }

在自定义单元格的类中，您需要覆盖awakeFromNib并告诉contentView其大小需要灵活

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

在自定义单元格覆盖layoutSubviews

中

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

在自定义单元格工具preferredLayoutSizeFittingSize的类中。这是您需要对正在布置的项目进行任何欺骗的地方。如果是标签，您需要告诉它首选的MaxWidth应该是什么。

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。如果你得到0或其他时髦的数字而不是你没有正确设置约束。

Answer 2

以下是Ray Wenderlich tutorial，其中介绍了如何使用AutoLayout动态调整UITableViewCell的大小。我认为UICollectionViewCell会是一样的。

但是，基本上，你最终会出列并配置一个原型单元并抓住它的高度。阅读完本文后，我决定 NOT 实现此方法，并编写一些清晰明确的大小调整代码。

这就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
}

<小时/> 编辑： 我对您的崩溃进行了一些研究，并决定在没有自定义XIB的情况下无法完成此操作。虽然这有点令人沮丧，但您应该能够从故事板剪切并粘贴到自定义的空XIB。

完成上述操作后，以下代码将帮助您：

//  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（以及一个非常基本的UICollectionViewCell子类和相关的XIB）给了我这个：

enter image description here

Answer 3

我们可以在没有xib的情况下维护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

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

为我找到的更简单的解决方案更新我的答案..

在我的情况下，我想修复宽度，并有可变高度单元格。我想要一个可以重复使用的解决方案来处理轮换并且不需要很多干预。

我得到的是，在集合单元格中覆盖（仅）systemLayoutFitting(...)（在本例中是我的基类），并首先击败UICollectionView在contentView上设置错误维度的努力为已知尺寸添加约束，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（这感觉就像一个bug）单元格本身的维度，但不是contentView - 否则会被限制为冲突的大小（因此约束以上）。为了计算正确的单元格大小，我对要浮动的维度使用较低的优先级，然后返回所需的高度以使内容适合我想要修复的宽度：

        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)
    }()
}

但这个宽度来自哪里？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，为了处理轮换，我实现trailCollectionDidChange以使布局无效：

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

最终结果如下：

我已发布a working sample here.

Answer 5

快速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：在这种大小确定的情况下配置数据时，我不建议设置图像。它给了我失真/不需要的结果。配置文本只会给我以下结果。

Answer 6

似乎这是一个很受欢迎的问题，所以我将尽我的微薄贡献。

以下代码是 Swift 4 解决方案，适用于无故事板设置。它利用了先前答案中的一些方法，因此可以防止因设备旋转而引起的“自动布局”警告。

对不起，如果代码示例有点长。我想提供一个由StackOverflow完全托管的“易于使用”的解决方案。如果您对帖子有任何建议-请分享想法，我将相应地更新。

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的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

我按照此SO中提到的步骤进行操作，一切都很好，除非我的集合视图具有较少的数据（文本）以使其足够宽。检查systemLyaoutSizeFittingSize中的文档，我有这个解决方案，所以我的单元格按照我的要求占用了宽度：

- (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);

Apple doc：

相当于发送-systemLayoutSizeFittingSize：withHorizontalFittingPriority：verticalFittingPriority：UILayoutPriorityFittingSizeLevel用于两个优先级。

根据Apple的文档：

，默认值“非常低”

当您发送 - [UIView systemLayoutSizeFittingSize：]时，将计算最接近目标大小（参数）的大小。 UILayoutPriorityFittingSizeLevel是视图要与该计算中的目标大小一致的优先级。它很低。通常不恰当地以此优先级进行约束。你想要更高或更低。

所以我的默认行为更改是使用UILayoutPriorityRequired强制宽度（水平拟合）。

Answer 8

按照bolnad answer进行第4步。

然后将所有其他步骤替换为：

，使其更简单

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 9

它对我有用，希望您也是如此。

*注意：我在Nib中使用了自动布局，请记住在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
    }

Answer 10

根据@ mbm29414的有用答案迅速获得4个答案。

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格（仅创建一次）并在初始化收集视图时注册XIB。

然后，您可以在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
}

UICollectionView - 动态单元格高度？

10 个答案:

设置：

`MultilineLabelCell.swift`

`ViewController.swift`