Ios 如何将UICollectionView的单元格居中对齐?
我目前正在为用户界面网格使用Ios 如何将UICollectionView的单元格居中对齐?,ios,uicollectionview,Ios,Uicollectionview,我目前正在为用户界面网格使用UICollectionView,效果很好。但是,我希望启用水平滚动。网格支持每页8个项目,当项目总数为(比如)4个时,应在启用水平滚动方向的情况下安排项目: 0 0 x x 0 0 x x 此处为0->收集项目 和x->空单元格 有没有一种方法可以使它们中心对齐,如: x 0 0 x x 0 0 x 让内容看起来更干净 此外,下面的安排可能也是我期待的解决方案 0 0 0 0 x x x x 我认为您可以通过实现以下内容来实现单线外观: - (UIEdgeIn
UICollectionView
,效果很好。但是,我希望启用水平滚动。网格支持每页8个项目,当项目总数为(比如)4个时,应在启用水平滚动方向的情况下安排项目:
0 0 x x
0 0 x x
此处为0->收集项目
和x->空单元格
有没有一种方法可以使它们中心对齐,如:
x 0 0 x
x 0 0 x
让内容看起来更干净
此外,下面的安排可能也是我期待的解决方案
0 0 0 0
x x x x
我认为您可以通过实现以下内容来实现单线外观:
- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section {
return UIEdgeInsetsMake(0, 100, 0, 0);
}
KTCenterFlowLayout *layout = [[KTCenterFlowLayout alloc] init];
[self.collectionView setCollectionViewLayout:layout];
你将不得不利用这个数字来找出如何将内容强制到一行中。第一个0是top edge参数,如果您想在屏幕上垂直居中显示内容,也可以调整该参数。我的应用程序中有一个标记栏,它使用
UICollectionView
&UICollectionViewFlowLayout
,其中一行单元格居中对齐
要获得正确的缩进,请从UICollectionView
的宽度中减去所有单元格的总宽度(包括间距),然后除以2
[........Collection View.........]
[..Cell..][..Cell..]
[____indent___] / 2
=
[_____][..Cell..][..Cell..][_____]
问题是这个函数-
-(UIEdgeInsets)集合视图:(UICollectionView*)集合视图布局:(UICollectionViewLayout*)集合视图布局插图索引:(NSInteger)部分代码>
在…之前被呼叫
-(UICollectionViewCell*)collectionView:(UICollectionView*)collectionView cellForItemAtIndexPath:(NSIndexPath*)indexPath代码>
…因此您无法迭代单元格以确定总宽度
相反,您需要再次计算每个单元格的宽度,在我的例子中,我使用[NSString sizeWithFont:…]
,因为我的单元格宽度是由UILabel本身决定的
- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section
{
CGFloat rightEdge = 0;
CGFloat interItemSpacing = [(UICollectionViewFlowLayout*)collectionViewLayout minimumInteritemSpacing];
for(NSString * tag in _tags)
rightEdge += [tag sizeWithFont:[UIFont systemFontOfSize:14]].width+interItemSpacing;
// To center the inter spacing too
rightEdge -= interSpacing/2;
// Calculate the inset
CGFloat inset = collectionView.frame.size.width-rightEdge;
// Only center align if the inset is greater than 0
// That means that the total width of the cells is less than the width of the collection view and need to be aligned to the center.
// Otherwise let them align left with no indent.
if(inset > 0)
return UIEdgeInsetsMake(0, inset/2, 0, 0);
else
return UIEdgeInsetsMake(0, 0, 0, 0);
}
不确定这在Xcode 5中是否是新的,但您现在可以通过Interface Builder打开大小检查器并在其中设置一个插入。这将避免您必须编写自定义代码来执行此操作,并应大幅提高找到正确偏移的速度。动态计算插入很容易,此代码将始终使单元格居中:
NSInteger const SMEPGiPadViewControllerCellWidth = 332;
...
- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section
{
NSInteger numberOfCells = self.view.frame.size.width / SMEPGiPadViewControllerCellWidth;
NSInteger edgeInsets = (self.view.frame.size.width - (numberOfCells * SMEPGiPadViewControllerCellWidth)) / (numberOfCells + 1);
return UIEdgeInsetsMake(0, edgeInsets, 0, edgeInsets);
}
- (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
{
[super willRotateToInterfaceOrientation:toInterfaceOrientation duration:duration];
[self.collectionView.collectionViewLayout invalidateLayout];
}
这里的顶级解决方案不适用于我,所以我提出了这个解决方案,它适用于任何具有流布局的水平滚动集合视图,并且只有一个部分:
- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section
{
// Add inset to the collection view if there are not enough cells to fill the width.
CGFloat cellSpacing = ((UICollectionViewFlowLayout *) collectionViewLayout).minimumLineSpacing;
CGFloat cellWidth = ((UICollectionViewFlowLayout *) collectionViewLayout).itemSize.width;
NSInteger cellCount = [collectionView numberOfItemsInSection:section];
CGFloat inset = (collectionView.bounds.size.width - (cellCount * cellWidth) - ((cellCount - 1)*cellSpacing)) * 0.5;
inset = MAX(inset, 0.0);
return UIEdgeInsetsMake(0.0, inset, 0.0, 0.0);
}
将其放入集合视图委托中。和其他答案相比,它考虑了更多的基本流布局设置,因而更通用
- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section
{
NSInteger cellCount = [collectionView.dataSource collectionView:collectionView numberOfItemsInSection:section];
if( cellCount >0 )
{
CGFloat cellWidth = ((UICollectionViewFlowLayout*)collectionViewLayout).itemSize.width+((UICollectionViewFlowLayout*)collectionViewLayout).minimumInteritemSpacing;
CGFloat totalCellWidth = cellWidth*cellCount + spacing*(cellCount-1);
CGFloat contentWidth = collectionView.frame.size.width-collectionView.contentInset.left-collectionView.contentInset.right;
if( totalCellWidth<contentWidth )
{
CGFloat padding = (contentWidth - totalCellWidth) / 2.0;
return UIEdgeInsetsMake(0, padding, 0, padding);
}
}
return UIEdgeInsetsZero;
}
-(UIEdgeInsets)集合视图:(UICollectionView*)集合视图布局:(UICollectionViewLayout*)集合视图布局插图索引:(NSInteger)部分
{
NSInteger cellCount=[collectionView.dataSource collectionView:collectionView numberofitemsinssection:section];
如果(细胞计数>0)
{
CGFloat单元格宽度=((UICollectionViewFlowLayout*)collectionViewLayout).itemSize.width+((UICollectionViewFlowLayout*)collectionViewLayout).最小发光材料间距;
CGFloat totalCellWidth=cellWidth*cellCount+间距*(cellCount-1);
CGFloat contentWidth=collectionView.frame.size.width-collectionView.contentInset.left-collectionView.contentInset.right;
if(总单元宽度UIEdgeInsets{
//翻译自Objective-C版本,网址:http://stackoverflow.com/a/27656363/309736
让cellCount=CGFloat(viewModel.getNumOfItemsInSection(0))
如果cellCount>0{
让flowLayout=collectionViewLayout为!UICollectionViewFlowLayout
设cellWidth=flowLayout.itemSize.width+flowLayout.MinimumItemSpacing
设totalCellWidth=cellWidth*cellCount+间距*(cellCount-1)
让contentWidth=collectionView.frame.size.width-collectionView.contentInset.left-collectionView.contentInset.right
if(总单元格宽度<内容宽度){
let padding=(contentWidth-totalCellWidth)/2.0
返回UIEdgeInsetsMake(0,填充,0,填充)
}
}
返回UIEdgeInsetsZero
}
}
您可以这样使用:
- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section {
return UIEdgeInsetsMake(0, 100, 0, 0);
}
KTCenterFlowLayout *layout = [[KTCenterFlowLayout alloc] init];
[self.collectionView setCollectionViewLayout:layout];
与其他答案类似,这是一个动态答案,应该适用于静态大小的单元格。我做的一个修改是,我将填充物放在两侧。如果我不这样做,我会遇到问题
目标-C
敏捷的
此外,如果您仍然遇到问题,请确保将最小行间距
和最小行间距
设置为相同的值,因为这些值似乎是相互关联的
UICollectionViewFlowLayout *flowLayout = (UICollectionViewFlowLayout *)self.collectionView.collectionViewLayout;
flowLayout.minimumInteritemSpacing = 20.0;
flowLayout.minimumLineSpacing = 20.0;
在Swift中,以下内容将通过在每个单元格的侧面应用正确数量的填充来均匀分布单元格。当然,您需要首先知道/设置单元格宽度
func collectionView(collectionView: UICollectionView,
layout collectionViewLayout: UICollectionViewLayout,
insetForSectionAtIndex section: Int) -> UIEdgeInsets {
var cellWidth : CGFloat = 110;
var numberOfCells = floor(self.view.frame.size.width / cellWidth);
var edgeInsets = (self.view.frame.size.width - (numberOfCells * cellWidth)) / (numberOfCells + 1);
return UIEdgeInsetsMake(0, edgeInsets, 60.0, edgeInsets);
}
另一种方法是设置collectionView.center.x
,如下所示:
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
if let
collectionView = collectionView,
layout = collectionView.collectionViewLayout as? UICollectionViewFlowLayout
{
collectionView.center.x = view.center.x + layout.sectionInset.right / 2.0
}
}
在这种情况下,只考虑适合我的右插图。Swift 2.0
对我来说很好
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAtIndex section: Int) -> UIEdgeInsets {
let edgeInsets = (screenWight - (CGFloat(elements.count) * 50) - (CGFloat(elements.count) * 10)) / 2
return UIEdgeInsetsMake(0, edgeInsets, 0, 0);
}
其中:
屏幕宽度:基本上是我的收藏宽度(全屏宽度)-我制作了常数:
让screenWight:CGFloat=UIScreen.mainScreen().bounds.width
因为self.view.bounds每次显示600-coz的大小
元素-单元格数组
50-我的手动单元格宽度
10-我的单元格之间的距离我的静态大小的集合视图单元格的解决方案,这些单元格的左右两侧都需要填充-
func collectionView(collectionView: UICollectionView,
layout collectionViewLayout: UICollectionViewLayout,
insetForSectionAtIndex section: Int) -> UIEdgeInsets {
let flowLayout = (collectionViewLayout as! UICollectionViewFlowLayout)
let cellSpacing = flowLayout.minimumInteritemSpacing
let cellWidth = flowLayout.itemSize.width
let cellCount = CGFloat(collectionView.numberOfItemsInSection(section))
let collectionViewWidth = collectionView.bounds.size.width
let totalCellWidth = cellCount * cellWidth
let totalCellSpacing = cellSpacing * (cellCount - 1)
let totalCellsWidth = totalCellWidth + totalCellSpacing
let edgeInsets = (collectionViewWidth - totalCellsWidth) / 2.0
return edgeInsets > 0 ? UIEdgeInsetsMake(0, edgeInsets, 0, edgeInsets) : UIEdgeInsetsMake(0, cellSpacing, 0, cellSpacing)
}
根据用户3676011的回答,我可以建议更详细的答案,但需要稍加修改。
此解决方案在Swift 2.0上非常有效
enum CollectionViewContentPosition {
case Left
case Center
}
var collectionViewContentPosition: CollectionViewContentPosition = .Left
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout,
insetForSectionAtIndex section: Int) -> UIEdgeInsets {
if collectionViewContentPosition == .Left {
return UIEdgeInsetsZero
}
// Center collectionView content
let itemsCount: CGFloat = CGFloat(collectionView.numberOfItemsInSection(section))
let collectionViewWidth: CGFloat = collectionView.bounds.width
let itemWidth: CGFloat = 40.0
let itemsMargin: CGFloat = 10.0
let edgeInsets = (collectionViewWidth - (itemsCount * itemWidth) - ((itemsCount-1) * itemsMargin)) / 2
return UIEdgeInsetsMake(0, edgeInsets, 0, 0)
}
这里面有个问题
(CGFloat(元素计数)*10)
应该在哪里提到额外的-1
。对于那些寻找中心对齐的解决方案的人,动态宽度collectionview单元格,就像我一样,我最终选择了mod
enum CollectionViewContentPosition {
case Left
case Center
}
var collectionViewContentPosition: CollectionViewContentPosition = .Left
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout,
insetForSectionAtIndex section: Int) -> UIEdgeInsets {
if collectionViewContentPosition == .Left {
return UIEdgeInsetsZero
}
// Center collectionView content
let itemsCount: CGFloat = CGFloat(collectionView.numberOfItemsInSection(section))
let collectionViewWidth: CGFloat = collectionView.bounds.width
let itemWidth: CGFloat = 40.0
let itemsMargin: CGFloat = 10.0
let edgeInsets = (collectionViewWidth - (itemsCount * itemWidth) - ((itemsCount-1) * itemsMargin)) / 2
return UIEdgeInsetsMake(0, edgeInsets, 0, 0)
}
// NOTE: Doesn't work for horizontal layout!
class CenterAlignedCollectionViewFlowLayout: UICollectionViewFlowLayout {
override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
guard let superAttributes = super.layoutAttributesForElements(in: rect) else { return nil }
// Copy each item to prevent "UICollectionViewFlowLayout has cached frame mismatch" warning
guard let attributes = NSArray(array: superAttributes, copyItems: true) as? [UICollectionViewLayoutAttributes] else { return nil }
// Constants
let leftPadding: CGFloat = 8
let interItemSpacing = minimumInteritemSpacing
// Tracking values
var leftMargin: CGFloat = leftPadding // Modified to determine origin.x for each item
var maxY: CGFloat = -1.0 // Modified to determine origin.y for each item
var rowSizes: [[CGFloat]] = [] // Tracks the starting and ending x-values for the first and last item in the row
var currentRow: Int = 0 // Tracks the current row
attributes.forEach { layoutAttribute in
// Each layoutAttribute represents its own item
if layoutAttribute.frame.origin.y >= maxY {
// This layoutAttribute represents the left-most item in the row
leftMargin = leftPadding
// Register its origin.x in rowSizes for use later
if rowSizes.count == 0 {
// Add to first row
rowSizes = [[leftMargin, 0]]
} else {
// Append a new row
rowSizes.append([leftMargin, 0])
currentRow += 1
}
}
layoutAttribute.frame.origin.x = leftMargin
leftMargin += layoutAttribute.frame.width + interItemSpacing
maxY = max(layoutAttribute.frame.maxY, maxY)
// Add right-most x value for last item in the row
rowSizes[currentRow][1] = leftMargin - interItemSpacing
}
// At this point, all cells are left aligned
// Reset tracking values and add extra left padding to center align entire row
leftMargin = leftPadding
maxY = -1.0
currentRow = 0
attributes.forEach { layoutAttribute in
// Each layoutAttribute is its own item
if layoutAttribute.frame.origin.y >= maxY {
// This layoutAttribute represents the left-most item in the row
leftMargin = leftPadding
// Need to bump it up by an appended margin
let rowWidth = rowSizes[currentRow][1] - rowSizes[currentRow][0] // last.x - first.x
let appendedMargin = (collectionView!.frame.width - leftPadding - rowWidth - leftPadding) / 2
leftMargin += appendedMargin
currentRow += 1
}
layoutAttribute.frame.origin.x = leftMargin
leftMargin += layoutAttribute.frame.width + interItemSpacing
maxY = max(layoutAttribute.frame.maxY, maxY)
}
return attributes
}
}
#define maxInteritemSpacing 6
#define minLineSpacing 3
@interface MyFlowLayout()<UICollectionViewDelegateFlowLayout>
@end
@implementation MyFlowLayout
- (instancetype)init
{
self = [super init];
if (self) {
self.minimumInteritemSpacing = 3;
self.minimumLineSpacing = minLineSpacing;
self.scrollDirection = UICollectionViewScrollDirectionVertical;
}
return self;
}
- (NSArray *) layoutAttributesForElementsInRect:(CGRect)rect {
NSArray *answer = [super layoutAttributesForElementsInRect:rect];
if (answer.count > 0) {
NSMutableArray<NSMutableArray<UICollectionViewLayoutAttributes *> *> *rows = [NSMutableArray array];
CGFloat maxY = -1.0f;
NSInteger currentRow = 0;
//add first item to row and set its maxY
[rows addObject:[@[answer[0]] mutableCopy]];
maxY = CGRectGetMaxY(((UICollectionViewLayoutAttributes *)answer[0]).frame);
for(int i = 1; i < [answer count]; ++i) {
//handle maximum spacing
UICollectionViewLayoutAttributes *currentLayoutAttributes = answer[i];
UICollectionViewLayoutAttributes *prevLayoutAttributes = answer[i - 1];
NSInteger maximumSpacing = maxInteritemSpacing;
NSInteger origin = CGRectGetMaxX(prevLayoutAttributes.frame);
if(origin + maximumSpacing + currentLayoutAttributes.frame.size.width < self.collectionViewContentSize.width) {
CGRect frame = currentLayoutAttributes.frame;
frame.origin.x = origin + maximumSpacing;
currentLayoutAttributes.frame = frame;
}
//handle center align
CGFloat currentY = currentLayoutAttributes.frame.origin.y;
if (currentY >= maxY) {
[self shiftRowToCenterForCurrentRow:rows[currentRow]];
//next row
[rows addObject:[@[currentLayoutAttributes] mutableCopy]];
currentRow++;
}
else {
//same row
[rows[currentRow] addObject:currentLayoutAttributes];
}
maxY = MAX(CGRectGetMaxY(currentLayoutAttributes.frame), maxY);
}
//mark sure to shift 1 row items
if (currentRow == 0) {
[self shiftRowToCenterForCurrentRow:rows[currentRow]];
}
}
return answer;
}
- (void)shiftRowToCenterForCurrentRow:(NSMutableArray<UICollectionViewLayoutAttributes *> *)currentRow
{
//shift row to center
CGFloat endingX = CGRectGetMaxX(currentRow.lastObject.frame);
CGFloat shiftX = (self.collectionViewContentSize.width - endingX) / 2.f;
for (UICollectionViewLayoutAttributes *attr in currentRow) {
CGRect shiftedFrame = attr.frame;
shiftedFrame.origin.x += shiftX;
attr.frame = shiftedFrame;
}
}
@end
let flow = UICollectionViewFlowLayout()
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
let numberOfItems = collectionView.numberOfItems(inSection: 0)
let combinedItemWidth:CGFloat = (CGFloat(numberOfItems) * flow.itemSize.width) + ((CGFloat(numberOfItems) - 1) * flow.minimumInteritemSpacing)
let padding = (collectionView.frame.size.width - combinedItemWidth) / 2
return UIEdgeInsetsMake(0, padding, 0, padding)
}
func refreshCollectionView(_ count: Int) {
let collectionViewHeight = collectionView.bounds.height
let collectionViewWidth = collectionView.bounds.width
let numberOfItemsThatCanInCollectionView = Int(collectionViewWidth / collectionViewHeight)
if numberOfItemsThatCanInCollectionView > count {
let totalCellWidth = collectionViewHeight * CGFloat(count)
let totalSpacingWidth: CGFloat = CGFloat(count) * (CGFloat(count) - 1)
// leftInset, rightInset are the global variables which I am passing to the below function
leftInset = (collectionViewWidth - CGFloat(totalCellWidth + totalSpacingWidth)) / 2;
rightInset = -leftInset
} else {
leftInset = 0.0
rightInset = -collectionViewHeight
}
collectionView.reloadData()
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
return UIEdgeInsetsMake(0, leftInset, 0, rightInset)
}
protocol HACenteredLayoutDelegate: UICollectionViewDataSource {
func getCollectionView() -> UICollectionView
func sizeOfCell(at index: IndexPath) -> CGSize
func contentInsets() -> UIEdgeInsets
}
class HACenteredLayout: UICollectionViewFlowLayout {
weak var delegate: HACenteredLayoutDelegate?
private var cache = [UICollectionViewLayoutAttributes]()
private var contentSize = CGSize.zero
override var collectionViewContentSize: CGSize { return self.contentSize }
required init(delegate: HACenteredLayoutDelegate) {
self.delegate = delegate
super.init()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
override func invalidateLayout() {
cache.removeAll()
super.invalidateLayout()
}
override func prepare() {
if cache.isEmpty && self.delegate != nil && self.delegate!.collectionView(self.delegate!.getCollectionView(), numberOfItemsInSection: 0) > 0 {
let insets = self.delegate?.contentInsets() ?? UIEdgeInsets.zero
var rows: [(width: CGFloat, count: Int)] = [(0, 0)]
let viewWidth: CGFloat = UIScreen.main.bounds.width
var y = insets.top
var unmodifiedIndexes = [IndexPath]()
for itemNumber in 0 ..< self.delegate!.collectionView(self.delegate!.getCollectionView(), numberOfItemsInSection: 0) {
let indexPath = IndexPath(item: itemNumber, section: 0)
let cellSize = self.delegate!.sizeOfCell(at: indexPath)
let potentialRowWidth = rows.last!.width + (rows.last!.count > 0 ? self.minimumInteritemSpacing : 0) + cellSize.width + insets.right + insets.left
if potentialRowWidth > viewWidth {
let leftOverSpace = max((viewWidth - rows[rows.count - 1].width)/2, insets.left)
for i in unmodifiedIndexes {
self.cache[i.item].frame.origin.x += leftOverSpace
}
unmodifiedIndexes = []
rows.append((0, 0))
y += cellSize.height + self.minimumLineSpacing
}
unmodifiedIndexes.append(indexPath)
let attribute = UICollectionViewLayoutAttributes(forCellWith: indexPath)
rows[rows.count - 1].count += 1
rows[rows.count - 1].width += rows[rows.count - 1].count > 1 ? self.minimumInteritemSpacing : 0
attribute.frame = CGRect(x: rows[rows.count - 1].width, y: y, width: cellSize.width, height: cellSize.height)
rows[rows.count - 1].width += cellSize.width
cache.append(attribute)
}
let leftOverSpace = max((viewWidth - rows[rows.count - 1].width)/2, insets.left)
for i in unmodifiedIndexes {
self.cache[i.item].frame.origin.x += leftOverSpace
}
self.contentSize = CGSize(width: viewWidth, height: y + self.delegate!.sizeOfCell(at: IndexPath(item: 0, section: 0)).height + insets.bottom)
}
}
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? {
if indexPath.item < self.cache.count {
return self.cache[indexPath.item]
}
return nil
}
}