关于UICollectionView横向分页滚动,cell左右排版功能的实现

实现了对UICollectionView横向滑动的时候UICollectionViewCell横向排列的功能，并带有分组功能
先看下效果图

废话不多说直接上代码

#import <UIKit/UIKit.h>@interface ELCVFlowLayout : UICollectionViewFlowLayout@end

#import "ELCVFlowLayout.h"@interface ELCVFlowLayout ()@property (nonatomic, copy) NSMutableDictionary *sectionDic;@property (strong, nonatomic) NSMutableArray *allAttributes;@end@implementation ELCVFlowLayout- (instancetype)init{    self = [super init];    if (self) {        self.scrollDirection = UICollectionViewScrollDirectionHorizontal;    }    return self;}- (void)prepareLayout{    [super prepareLayout];    _sectionDic = [NSMutableDictionary dictionary];    self.allAttributes = [NSMutableArray array];    //获取section的数量    NSUInteger section = [self.collectionView numberOfSections];    for (int sec = 0; sec < section; sec++) {        //获取每个section的cell个数        NSUInteger count = [self.collectionView numberOfItemsInSection:sec];        for (NSUInteger item = 0; item<count; item++) {            NSIndexPath *indexPath = [NSIndexPath indexPathForItem:item inSection:sec];            //重新排列            UICollectionViewLayoutAttributes *attributes = [self layoutAttributesForItemAtIndexPath:indexPath];            [self.allAttributes addObject:attributes];        }    }}- (CGSize)collectionViewContentSize{    //每个section的页码的总数    NSInteger actualLo = 0;    for (NSString *key in [_sectionDic allKeys]) {        actualLo += [_sectionDic[key] integerValue];    }    return CGSizeMake(actualLo*self.collectionView.frame.size.width, self.collectionView.contentSize.height);}- (void)applyLayoutAttributes:(UICollectionViewLayoutAttributes *)attributes{    if(attributes.representedElementKind != nil)    {        return;    }    /*修改by lixinkai 2017.6.30    下面这两个方法 itemW、itemH     解决了同一个UICollectionView使用不同UICollectionViewCell的问题     */    //attributes 的宽度    CGFloat itemW = attributes.frame.size.width;    //attributes 的高度    CGFloat itemH = attributes.frame.size.height;    //collectionView 的宽度    CGFloat width = self.collectionView.frame.size.width;    //collectionView 的高度    CGFloat height = self.collectionView.frame.size.height;    //每个attributes的下标值 从0开始    NSInteger itemIndex = attributes.indexPath.item;    CGFloat stride = (self.scrollDirection == UICollectionViewScrollDirectionHorizontal) ? width : height;    //获取现在的attributes是第几组    NSInteger section = attributes.indexPath.section;    //获取每个section的item的个数    NSInteger itemCount = [self.collectionView numberOfItemsInSection:section];    CGFloat offset = section * stride;    //计算x方向item个数    NSInteger xCount = (width / itemW);    //计算y方向item个数    NSInteger yCount = (height / itemH);    //计算一页总个数    NSInteger allCount = (xCount * yCount);    //获取每个section的页数，从0开始    NSInteger page = itemIndex / allCount;    //余数，用来计算item的x的偏移量    NSInteger remain = (itemIndex % xCount);    //取商，用来计算item的y的偏移量    NSInteger merchant = (itemIndex-page*allCount)/xCount;    //x方向每个item的偏移量    CGFloat xCellOffset = remain * itemW;    //y方向每个item的偏移量    CGFloat yCellOffset = merchant * itemH;    //获取每个section中item占了几页    NSInteger pageRe = (itemCount % allCount == 0)? (itemCount / allCount) : (itemCount / allCount) + 1;    //将每个section与pageRe对应，计算下面的位置    [_sectionDic setValue:@(pageRe) forKey:[NSString stringWithFormat:@"%ld", section]];    if(self.scrollDirection == UICollectionViewScrollDirectionHorizontal) {        NSInteger actualLo = 0;        //将每个section中的页数相加        for (NSString *key in [_sectionDic allKeys]) {            actualLo += [_sectionDic[key] integerValue];        }        //获取到的最后的数减去最后一组的页码数        actualLo -= [_sectionDic[[NSString stringWithFormat:@"%ld", [_sectionDic allKeys].count-1]] integerValue];        xCellOffset += page*width + actualLo*width;    } else {        yCellOffset += offset;    }    attributes.frame = CGRectMake(xCellOffset, yCellOffset, itemW, itemH);}- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath{//    UICollectionViewLayoutAttributes *attr = [UICollectionViewLayoutAttributes  layoutAttributesForCellWithIndexPath:indexPath];   UICollectionViewLayoutAttributes *attr = [super layoutAttributesForItemAtIndexPath:indexPath].copy;    [self applyLayoutAttributes:attr];    return attr;}- (NSArray<UICollectionViewLayoutAttributes *> *)layoutAttributesForElementsInRect:(CGRect)rect{    return self.allAttributes;}@end

也可以直接下载
https://github.com/elite-kai/ELCVFlowLayout