我刚开始学习 UICollectionViews。我想知道是否有人知道如何指定collectionview 中的列数。默认设置为 3（iPhone/纵向）。我查看了文档，似乎找不到简明的答案。
【问题讨论】：
UICollectionView 用作网格，因为我知道我只想要 4 列。我通过使我的单元格具有一定的大小和它们之间的间距来做到这一点，因此无论方向如何，collectionview 都只显示 4 列。这与您需要的相似吗？
标签： ios objective-c xcode uicollectionview uicollectionviewcell
在 Swift 5 和 iOS 12.3 中，您可以使用 4 个以下实现 来设置 UICollectionView 中每行的项目数，同时管理插入和大小更改（包括旋转） .
UICollectionViewFlowLayout 并使用UICollectionViewFlowLayout 的itemSize 属性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) -> 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) -> Int {
return 59
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath)
cell.backgroundColor = UIColor.orange
return cell
}
}
UICollectionViewFlowLayout的itemSize方法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) -> Int {
return 59
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> 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)
}
}
UICollectionViewDelegateFlowLayout的collectionView(_:layout:sizeForItemAt:)方法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) -> UIEdgeInsets {
return UIEdgeInsets(top: inset, left: inset, bottom: inset, right: inset)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
return minimumLineSpacing
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
return minimumInteritemSpacing
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> 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) -> Int {
return 59
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> 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)
}
}
UICollectionViewFlowLayout 并使用UICollectionViewFlowLayout 的estimatedItemSize 属性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) -> Int {
return items.count
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> 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) -> 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) -> [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 < $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 < $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) -> 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) -> UICollectionViewLayoutAttributes {
label.preferredMaxLayoutWidth = layoutAttributes.size.width - contentView.layoutMargins.left - contentView.layoutMargins.right
layoutAttributes.bounds.size.height = contentView.systemLayoutSizeFitting(UIView.layoutFittingCompressedSize).height
return layoutAttributes
}
*/
}
【讨论】：
CollectionView 非常强大，但它们是有代价的。很多，还有很多选择。正如 omz 所说：
您可以通过多种方式更改列数
我建议实现<UICollectionViewDelegateFlowLayout> 协议，让您可以访问以下方法，您可以更好地控制UICollectionView 的布局，而无需对其进行子类化：
collectionView:layout:insetForSectionAtIndex:collectionView:layout:minimumInteritemSpacingForSectionAtIndex:collectionView:layout:minimumLineSpacingForSectionAtIndex:collectionView:layout:referenceSizeForFooterInSection:collectionView:layout:referenceSizeForHeaderInSection:collectionView:layout:sizeForItemAtIndexPath:此外，实施以下方法将强制您的 UICollectionView 在方向更改时更新其布局：（假设您想为横向调整单元格的大小并使其拉伸）
-(void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation
duration:(NSTimeInterval)duration{
[self.myCollectionView.collectionViewLayout invalidateLayout];
}
另外，这里有 2 个关于 UICollectionViews 的非常好的教程：
http://www.raywenderlich.com/22324/beginning-uicollectionview-in-ios-6-part-12
【讨论】：
collectionView:layout:sizeForItemAtIndexPath:？
new GridLayoutManager(mContext, 4))（4列），非常简单，或者直接使用LinearLayoutManager（当然只有1列）
我在UICollectionViewController 上实现了UICollectionViewDelegateFlowLayout，并覆盖了负责确定单元格大小的方法。然后我将屏幕宽度与我的列要求分开。例如，我想在每个屏幕尺寸上有 3 列。所以这就是我的代码的样子 -
- (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;
}
【讨论】：
扩展菜鸟的答案：
func collectionView(collectionView: UICollectionView,
layout collectionViewLayout: UICollectionViewLayout,
sizeForItemAtIndexPath indexPath: NSIndexPath) -> 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)
}
这允许单元格之间的任何间距。它假定一个名为numberOfItemsPerRow 的Int 成员变量，并且所有单元格都是正方形且大小相同。正如 jhilgert00 的回答中所述，我们还必须对方向变化做出反应，但现在使用 viewWillTransitionToSize 因为 willRotateToInterfaceOrientation 已被贬值。
【讨论】：
这是 Swift 3 或更高版本的工作代码，具有两列布局：
func collectionView(_ collectionView: UICollectionView,
layout collectionViewLayout: UICollectionViewLayout,
sizeForItemAt indexPath: IndexPath) -> 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)
}
随意将“nbCol”更改为您想要的列数。
【讨论】：
更新到 Swift 5+ iOS 13
Collectionview Estimate Size 必须为none
声明单元格的边距
let margin: CGFloat = 10
在 viewDidLoad 中配置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 方法sizeForItemAt
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> 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)
}
【讨论】：
如果你懒惰使用委托。
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：也应该在轮换后调用
【讨论】：
更新到 Swift 3：
我更喜欢对特定的列号和行号使用自定义布局，而不是流布局。因为：
普通单元格和标题单元格：（将 UILabel 作为 IBOutlet 添加到您的 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
}
}
自定义布局：
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) > cellWidth {
self.cellWidth = (self.collectionView?.bounds.size.width)!/CGFloat(self.numberOfColumns)
}
*/
for row in 0..<self.numberOfRows {
var row_temp = [UICollectionViewLayoutAttributes]()
for column in 0..<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) -> [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) -> Int {
return 20
}
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 20
}
override func numberOfItems(inSection section: Int) -> Int {
return 20
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> 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)")
}
}
使用 ViewController 中的 CollectionView：
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()
}
}
你终于可以拥有精美的 CollectionView 了！
【讨论】：
由于UICollectionView 非常灵活，您可以通过多种方式更改列数，具体取决于您使用的布局类型。
UICollectionViewFlowLayout（这可能是您正在使用的）没有直接指定列数（因为它取决于视图大小/方向）。更改它的最简单方法是设置itemSize 属性和/或minimumInteritemSpacing/minimumLineSpacing。
【讨论】：
斯威夫特 3.0。适用于水平和垂直滚动方向和可变间距
指定列数
let numberOfColumns: CGFloat = 3
配置flowLayout 渲染指定的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)
}
【讨论】：
这一切都与您要绘制的布局有关。您可以创建从 UICollectionViewFlowLayout 继承的自定义类。目前没有任何直接的方法来设置列。如果你想实现这种功能，你需要手动完成。您需要在自定义流布局类中处理它。
现在会出现一个问题，您将如何做到这一点？如果您不想打扰单元格框架，您可以调整
collectionView:layout:minimumInteritemSpacingForSectionAtIndex:
collectionView:layout:minimumLineSpacingForSectionAtIndex:
另一种方法是为您提供自己的单元格位置。通过覆盖以下两种方法，它们将在您的布局形成期间被调用。
- (NSArray*)layoutAttributesForElementsInRect:(CGRect)rect
- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)path
UICollectionViewLayoutAttributes 是处理单元格位置、框架、Zindex 等的类
【讨论】：
此答案适用于 swift 3.0 -->
首先符合协议：
UICollectionViewDelegateFlowLayout
然后添加这些方法：
//this method is for the size of items
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> 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) -> UIEdgeInsets {
return UIEdgeInsetsMake(0,0,0,0)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
return 0
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
return 0
}
【讨论】：
首先添加 UICollectionViewDelegateFlowLayout 作为协议。
然后：
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize
{
var columnCount = 3
let width = (view.frame.width - 20) / columnCount
return CGSize(width: width, height: width)
}
【讨论】：
我只是想附加到 Imanou Petit 的答案 #2。为了确保无论屏幕宽度如何，边距都是准确的，我使用具有所需边距的迭代求解器，并将列数作为输入。我还添加了一个方向标志，用于将它们的最终边距与目标进行比较。
迭代求解器如下所示，返回单元格宽度和边距。
private func iterativeCellSpacing(targetMargins : CGFloat,
cellsPerRow : Int,
isMinTarget : Bool) -> (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) > 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)
}
我这样称呼它：
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)
...
}
然后我将 cellWidth 和 margin 值应用到流布局中：
extension MyCollectionController : UICollectionViewDelegateFlowLayout
{ func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize { 返回CGSize（宽度：cellWidth，高度：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) -> UIEdgeInsets
{
return UIEdgeInsetsMake(margin, margin, margin, margin)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat
{
return margin
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat
{
return margin
}
}
希望这会有所帮助。可能有一种更简单的方法可以确保边距准确，但这是一种方法。此外，此代码尚未针对允许旋转集合视图的设备进行测试。
谢谢，
【讨论】：
完美的解决方案是 使用 UICollectionViewDelegateFlowLayout 但是你可以很容易地计算单元格宽度并划分你想要的列数
棘手的是使宽度没有分数
(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;}
【讨论】：
我做了一个集合布局。
要使分隔符可见，请将集合视图的背景颜色设置为灰色。 每节一行。
用途：
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
布局：
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 <= 0
{
cellHeight = (collectionView.bounds.height - seperator*CGFloat(numberOfSections-1))/CGFloat(numberOfSections)
}
for section in 0..<collectionView.numberOfSections {
let numberOfItems = collectionView.numberOfItems(inSection: section)
let cellWidth2 : CGFloat
if cellWidth <= 0
{
cellWidth2 = (collectionView.bounds.width - seperator*CGFloat(numberOfItems-1))/CGFloat(numberOfItems)
}
else
{
cellWidth2 = cellWidth
}
for row in 0..<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 <= 0)
{
return collectionView.bounds.size
}
let width:CGFloat
if cellWidth <= 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) -> [UICollectionViewLayoutAttributes]? {
var layoutAttributes = [UICollectionViewLayoutAttributes]()
for attributes in cache {
if attributes.frame.intersects(rect) {
layoutAttributes.append(attributes)
}
}
return layoutAttributes
}
override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
return cache[indexPath.item]
}
}
【讨论】：
试试这个，它非常适合我，
按照以下步骤操作：
1.在 .h 文件中定义值。
#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
或
#define kNoOfColumsForCollection 3
#define kCollectionViewCellWidthHieght (self.view.frame.size.width - 6*kNoOfColumsForCollection)/kNoOfColumsForCollection
2.在collection View Layout数据源方法中添加代码如下，
#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);
}
希望这对某些人有所帮助。
【讨论】：