IOS15瀑布流布局

环境

ios 15
xcode 13.0

效果图

核心源码:
我这里使用的nib，storyBoard加载的。

//
//  LJWaterflowLayout.m
//  WaterFlowDemo
//
//  Created by lujun on 2021/11/28.
//
#import "LJWaterflowLayout.h"
static const CGFloat LJDefaultColumnCount = 3;
static const CGFloat LJDefaultColumnMargin = 10;
static const CGFloat LJDefaultRowMargin = 10;
static const UIEdgeInsets LJDefaultEdgeInsets = {10,10,10,10};
@interface LJWaterflowLayout()
@property(nonatomic,strong)NSMutableArray *attrsArr;
@property (nonatomic, assign) CGFloat contentHeight;
@property(nonatomic,strong)NSMutableArray *columnHeights;
- (CGFloat)rowMargin;
- (CGFloat)columnMargin;
- (NSInteger)columnCount;
- (UIEdgeInsets)edgeInsets;
@end
@implementation LJWaterflowLayout
- (CGFloat)rowMargin
{
    if ([self.delegate respondsToSelector:@selector(rowMarginInWaterflowLayout:)]) {
        return [self.delegate rowMarginInWaterflowLayout:self];
    } else {
        return LJDefaultRowMargin;
    }
}

- (CGFloat)columnMargin
{
    if ([self.delegate respondsToSelector:@selector(columnMarginInWaterflowLayout:)]) {
        return [self.delegate columnMarginInWaterflowLayout:self];
    } else {
        return LJDefaultColumnMargin;
    }
}

- (NSInteger)columnCount
{
    if ([self.delegate respondsToSelector:@selector(columnCountInWaterflowLayout:)]) {
        return [self.delegate columnCountInWaterflowLayout:self];
    } else {
        return LJDefaultColumnCount;
    }
}

- (UIEdgeInsets)edgeInsets
{
    if ([self.delegate respondsToSelector:@selector(edgeInsetsInWaterflowLayout:)]) {
        return [self.delegate edgeInsetsInWaterflowLayout:self];
    } else {
        return LJDefaultEdgeInsets;
    }
}

- (void)prepareLayout{
    [super prepareLayout];
    self.contentHeight = 0;
    //[self.collectionView setShowsVerticalScrollIndicator:NO];
    [self.columnHeights removeAllObjects];
    for(NSInteger i=0;i<LJDefaultColumnCount;i++){
        [self.columnHeights addObject:@(LJDefaultEdgeInsets.top)];
    }
    [self.attrsArr removeAllObjects];
    NSInteger count = [self.collectionView numberOfItemsInSection:0];
    for(NSInteger i = 0;i < count; i++){
        NSIndexPath *indexPath = [NSIndexPath indexPathForItem:i inSection:0];
        UICollectionViewLayoutAttributes *attrs = [self layoutAttributesForItemAtIndexPath:indexPath];
        [self.attrsArr addObject:attrs];
     }
}

- (NSArray<__kindof UICollectionViewLayoutAttributes *> *)layoutAttributesForElementsInRect:(CGRect)rect{
    return  self.attrsArr;
}

- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath{
    // 创建布局属性
    UICollectionViewLayoutAttributes *attrs = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:indexPath];
    // collectionView的宽度
//    CGFloat collectionViewW = [UIScreen mainScreen].bounds.size.width;
    CGFloat collectionViewW = self.collectionView.frame.size.width;
    
    // 设置布局属性的frame
    CGFloat w = (collectionViewW - self.edgeInsets.left - self.edgeInsets.right - (self.columnCount - 1) * self.columnMargin) / self.columnCount;
    CGFloat h = [self.delegate waterflowLayout:self heightForItemAtIndex:indexPath.item itemWidth:w];
    // 找出高度最短的那一列
    NSInteger destColumn = 0;
    CGFloat minColumnHeight = [self.columnHeights[0] doubleValue];
    for (NSInteger i = 1; i < self.columnCount; i++) {
        // 取得第i列的高度
        CGFloat columnHeight = [self.columnHeights[i] doubleValue];
        if (minColumnHeight > columnHeight) {
            minColumnHeight = columnHeight;
            destColumn = i;
        }
    }
    CGFloat x = self.edgeInsets.left + destColumn * (w + self.columnMargin);
    CGFloat y = minColumnHeight;
    if (y != self.edgeInsets.top) {
        y += self.rowMargin;
    }
    attrs.frame = CGRectMake(x, y, w, h);
    // 更新最短那列的高度
    self.columnHeights[destColumn] = @(CGRectGetMaxY(attrs.frame));
    // 记录内容的高度
    CGFloat columnHeight = [self.columnHeights[destColumn] doubleValue];
    if (self.contentHeight < columnHeight) {
        self.contentHeight = columnHeight;
    }
    return attrs;
}

- (CGSize)collectionViewContentSize{
    return CGSizeMake(0, self.contentHeight + self.edgeInsets.bottom);
}
- (NSMutableArray *)columnHeights{
    if(!_columnHeights){
        _columnHeights = [NSMutableArray array];
    }
    return _columnHeights;
}
- (NSMutableArray *)attrsArr{
    if(!_attrsArr){
        _attrsArr = [NSMutableArray array];
    }
    
    return _attrsArr;
}
@end

第二段

#import "MJExtension.h"
#import "LJShop.h"
//
//  ViewController.m
//  WaterFlowDemo
//
//  Created by lujun on 2021/11/28.
//
#import "ViewController.h"
#import "MJRefresh.h"
#import "LJShopCell.h"
#import "LJWaterflowLayout.h"
//#import "UIImageView+WebCache.h"
#define k_title_color [UIColor whiteColor]
#define k_main_tab_bar_color [UIColor redColor]
#define TEXT_BIG_S_FONT18 [UIFont systemFontOfSize:24]
@interface ViewController () <LJWaterflowLayoutDelegate>
@property(nonatomic,strong)NSMutableArray *shops;
@end
@implementation ViewController
- (NSMutableArray *)shops{
    if(!_shops){
        _shops = [NSMutableArray array];
    }
    return _shops;
}
static NSString * const reuseIdentifier = @"shop";
- (void)viewDidLoad {
    [super viewDidLoad];
    [self setupLayout];
    [self setupRefresh];
    if (@available(iOS 15.0, *)) {
        UINavigationBarAppearance *appperance = [[UINavigationBarAppearance alloc] init];
        //添加背景色
        appperance.backgroundColor = k_main_tab_bar_color;
        appperance.shadowImage = [[UIImage alloc]init];
        appperance.shadowColor = nil;
        //设置字体颜色大小
        [appperance setTitleTextAttributes:@{NSForegroundColorAttributeName:k_title_color,NSFontAttributeName:TEXT_BIG_S_FONT18}];
        self.navigationController.navigationBar.standardAppearance = appperance;
        self.navigationController.navigationBar.scrollEdgeAppearance = appperance;
        self.navigationController.navigationBar.compactAppearance = appperance;
        self.navigationController.navigationBar.compactScrollEdgeAppearance = appperance;
    }
     self.navigationItem.title = @"瀑布流布局";
//   [self.collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:reuseIdentifier];
    [self.collectionView registerNib:[UINib nibWithNibName:NSStringFromClass([LJShopCell class]) bundle:nil] forCellWithReuseIdentifier:reuseIdentifier];
   LJWaterflowLayout * watet  = (LJWaterflowLayout *) [self.collectionView collectionViewLayout];
    watet.delegate = self;
}
- (CGFloat)waterflowLayout:(LJWaterflowLayout *)waterflowLayout heightForItemAtIndex:(NSUInteger)index itemWidth:(CGFloat)itemWidth{
//    NSLog(@"%s",__func__);
//    NSLog(@"大军");
    LJShop *shop = self.shops[index];
    return  itemWidth * shop.h / shop.w;
}
-(void)setupLayout{
    
}
-(void)setupRefresh{
    self.collectionView.header = [MJRefreshNormalHeader headerWithRefreshingTarget:self refreshingAction:@selector(loadNewShops)];
    [self.collectionView.header beginRefreshing];
    self.collectionView.footer = [MJRefreshAutoNormalFooter footerWithRefreshingTarget:self refreshingAction:@selector(loadMoreShops)];
    self.collectionView.footer.hidden = NO;
}
-(void)loadMoreShops{
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1.0*NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        NSArray *shops = [LJShop objectArrayWithFilename:@"mogujie.plist"];
       // [self.shops removeAllObjects];
        [self.shops addObjectsFromArray:shops];
        [self.collectionView reloadData];
        [self.collectionView.footer endRefreshing];
     });
}
-(void)loadNewShops{
     dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1.0*NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        NSArray *shops = [LJShop objectArrayWithFilename:@"mogujie.plist"];
        [self.shops removeAllObjects];
        [self.shops addObjectsFromArray:shops];
        [self.collectionView reloadData];
        [self.collectionView.header endRefreshing];
     });
}
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
   return 1;
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
    self.collectionView.footer.hidden = self.shops.count == 0;
    return self.shops.count;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    LJShopCell *cell  = [collectionView dequeueReusableCellWithReuseIdentifier:reuseIdentifier forIndexPath:indexPath];
    cell.shop = self.shops[indexPath.item];
    return cell;
}
#pragma mark - WaterFlowLayout的代理方法，总共4个
- (CGFloat)rowMarginInWaterflowLayout:(LJWaterflowLayout *)waterflowLayout{
    return  10;
}
- (CGFloat)columnCountInWaterflowLayout:(LJWaterflowLayout *)waterflowLayout{
    return 3;
}
@end