iOS 瀑布流的Demo

                      
/**
 * 瀑布流Demo的主要代码，若想看完整的代码请到下面链接去下载
 *
 * 链接: https://pan.baidu.com/s/1slByAHB 密码: r3q6
 */
#import <UIKit/UIKit.h>

@interface AppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;


@end

#import "AppDelegate.h"
#import "RootViewController.h"
@interface AppDelegate ()

@end

@implementation AppDelegate


- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    // Override point for customization after application launch.
    self.window.backgroundColor = [UIColor whiteColor];
    
    self.window.rootViewController = [[RootViewController alloc] init];
    
    [self.window makeKeyAndVisible];
    return YES;
}

@end

#import <UIKit/UIKit.h>

@interface RootViewController : UIViewController

@end

#import "RootViewController.h"
#import "LFWaterfallLayout.h"
#import "XMGShop.h"
#import "MJExtension.h"
#import "MJRefresh.h"
#import "XMGShopCell.h"
@interface RootViewController ()<UICollectionViewDataSource,LFWaterfallLayoutDelegate>

@property (nonatomic , strong) UICollectionView *collectionView;
/**
 *  所有商品数据
 */
@property (nonatomic , strong) NSMutableArray *shops;

@end

@implementation RootViewController

static NSString *const identifier = @"waterfall";

- (NSMutableArray *)shops{
    if (!_shops) {
        _shops = [NSMutableArray array];
    }
    return _shops;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    
    [self setupLayout];
    
    [self setupRefresh];
}

- (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 = YES;
}

- (void)loadNewShops{
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        NSArray *shops = [XMGShop objectArrayWithFilename:@"1.plist"];
        NSLog(@"%@",shops);
        [self.shops removeAllObjects];
        [self.shops addObjectsFromArray:shops];
        // 刷新数据
        [self.collectionView reloadData];
        [self.collectionView.header endRefreshing];
    });
}

- (void)loadMoreShops{
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        NSArray *shops = [XMGShop objectArrayWithFilename:@"1.plist"];
        [self.shops addObjectsFromArray:shops];
        // 刷新数据
        [self.collectionView reloadData];
        [self.collectionView.footer endRefreshing];
    });
}


- (void)setupLayout{
    // 创建布局
    LFWaterfallLayout *layout = [[LFWaterfallLayout alloc] init];
    layout.delegate = self;
    // 创建collecView
    self.collectionView = [[UICollectionView alloc] initWithFrame:self.view.bounds collectionViewLayout:layout];
    self.collectionView.backgroundColor = [UIColor whiteColor];
    self.collectionView.dataSource = self;
    [self.view addSubview:self.collectionView];
    // 注册
    [self.collectionView registerNib:[UINib nibWithNibName:NSStringFromClass([XMGShopCell class]) bundle:nil] forCellWithReuseIdentifier:identifier];
}

#pragma mark -- UICollectionViewDataSource --
- (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{
    XMGShopCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];
    cell.shop = self.shops[indexPath.item];
    
    return cell;
}

#pragma mark -- LFWaterfallLayoutDelegate --
- (CGFloat)waterflowLayout:(LFWaterfallLayout *)waterflowLayout heightForItemAtIndex:(NSUInteger)index itemWidth:(CGFloat)itemWidth{
    XMGShop *shop = self.shops[index];
    return itemWidth * shop.h / shop.w ;
}

//- (CGFloat)rowMarginInWaterflowLayout:(LFWaterfallLayout *)waterflowLayout{
//    return 30;
//}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}


@end

#import <UIKit/UIKit.h>
@class LFWaterfallLayout;

@protocol LFWaterfallLayoutDelegate <NSObject>

@required
- (CGFloat)waterflowLayout:(LFWaterfallLayout *)waterflowLayout heightForItemAtIndex:(NSUInteger)index itemWidth:(CGFloat)itemWidth;

@optional
- (CGFloat)columnCountInWaterflowLayout:(LFWaterfallLayout *)waterflowLayout;
- (CGFloat)columnMarginInWaterflowLayout:(LFWaterfallLayout *)waterflowLayout;
- (CGFloat)rowMarginInWaterflowLayout:(LFWaterfallLayout *)waterflowLayout;
- (UIEdgeInsets)edgeInsetsInWaterflowLayout:(LFWaterfallLayout *)waterflowLayout;
@end

@interface LFWaterfallLayout : UICollectionViewLayout

@property (nonatomic , weak) id<LFWaterfallLayoutDelegate> delegate;

@end

#import "LFWaterfallLayout.h"

static const NSInteger LFDefaultColumnCount = 3;//默认的列数
static const CGFloat LFDefaultColumnMargin = 10;//每一列之间的间距
static const CGFloat LFDefaultRowMargin = 10;//每一行之间的间距
static const UIEdgeInsets LFDefaultEdgeInsets = {10,10,10,10};//边缘间距

@interface LFWaterfallLayout ()
/**
 * 存放所有cell的布局属性
 */
@property (nonatomic , strong) NSMutableArray *attrsArray;
/**
 * 存放所有列的当前高度
 */
@property (nonatomic , strong) NSMutableArray *columnHeights;

- (CGFloat)rowMargin;
- (CGFloat)columnMargin;
- (NSInteger)columnCount;
- (UIEdgeInsets)endgeInsets;

@end

@implementation LFWaterfallLayout

#pragma mark -- 数据处理 -- 
- (CGFloat)rowMargin{
    if ([self.delegate respondsToSelector:@selector(rowMarginInWaterflowLayout:)]) {
        return [self.delegate rowMarginInWaterflowLayout:self];
    }else{
        return LFDefaultRowMargin;
    }
}

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

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

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

}

- (NSMutableArray *)attrsArray{
    if (!_attrsArray) {
        _attrsArray = [NSMutableArray array];
    }
    return _attrsArray;
}

- (NSMutableArray *)columnHeights{
    if (!_columnHeights) {
        _columnHeights = [NSMutableArray array];
    }
    return _columnHeights;
}

/**
 * 初始化
 */
- (void)prepareLayout{
    [super prepareLayout];
    // 清除以前计算的所有高度
    [self.columnHeights removeAllObjects];
    for (NSInteger i = 0; i < self.columnCount; i++) {
        [self.columnHeights addObject:@(self.endgeInsets.top)];
    }
    
    // 清除之前所有的布局属性
    [self.attrsArray removeAllObjects];
    
    // 开始创建每一个cell对应的布局属性
    NSInteger count = [self.collectionView numberOfItemsInSection:0];
    
    for (NSInteger i = 0 ;i < count;i++) {
        // 创建位置
        NSIndexPath *indexPath = [NSIndexPath indexPathForItem:i inSection:0];
        
       // 获取indexPath位置对应cell的属性
        UICollectionViewLayoutAttributes *attributes = [self layoutAttributesForItemAtIndexPath:indexPath];
        
        [self.attrsArray addObject:attributes];
    }
}

/**
 * 决定cell的布局
 */
- (NSArray<UICollectionViewLayoutAttributes *> *)layoutAttributesForElementsInRect:(CGRect)rect{
   
    return self.attrsArray;
}

/**
 * 返回indexPath位置cell对应的布局属性
 */
- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath{
    // 创建布局属性
    UICollectionViewLayoutAttributes *attributes = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:indexPath];
    //collectionView的宽度
    CGFloat collectionViewWidth = self.collectionView.frame.size.width;
    
    
    // 找出高度最短的那一列
    NSInteger shortestColumn = 0;
    // 找出最小高度
    CGFloat minColumnHeight = [self.columnHeights[0] doubleValue];
    for (NSInteger i = 1 ; i < self.columnCount; i++) {
        // 取出第i列的高度
        CGFloat columnHeight = [self.columnHeights[i] doubleValue];
        // 比较大小
        if (minColumnHeight > columnHeight) {
            minColumnHeight = columnHeight;
            shortestColumn = i;
        }
    }
    // 宽度
    CGFloat width = (collectionViewWidth - self.endgeInsets.left - self.endgeInsets.right - (self.columnCount - 1) *self.columnMargin) / self.columnCount;
    // x坐标
    CGFloat x = self.endgeInsets.left + shortestColumn * (width + self.columnMargin);
    // y坐标
    CGFloat y = minColumnHeight;
    if (y != self.endgeInsets.top) {
        y += self.rowMargin;
    }
    
    // 高度
    CGFloat height = [self.delegate waterflowLayout:self heightForItemAtIndex:indexPath.item itemWidth:width];
    //设置布局属性的frame
    attributes.frame = CGRectMake(x,y, width, height);
    
    // 更新高度
    self.columnHeights[shortestColumn] = @(CGRectGetMaxY(attributes.frame));
    
    return attributes;
}

- (CGSize)collectionViewContentSize{
   
    // 找出最大高度
    CGFloat maxColumnHeight = [self.columnHeights[0] doubleValue];
    for (NSInteger i = 1 ; i < self.columnCount; i++) {
        // 取出第i列的高度
        CGFloat columnHeight = [self.columnHeights[i] doubleValue];
        // 比较大小
        if (maxColumnHeight < columnHeight) {
            maxColumnHeight = columnHeight;
        }
    }
    return CGSizeMake(0, maxColumnHeight + self.endgeInsets.bottom);
}

@end

#import <UIKit/UIKit.h>

@interface XMGShop : NSObject
@property (nonatomic, assign) CGFloat w;
@property (nonatomic, assign) CGFloat h;
@property (nonatomic, copy) NSString *img;
@property (nonatomic, copy) NSString *price;
@end

#import "XMGShop.h"

@implementation XMGShop

@end

#import <UIKit/UIKit.h>
@class XMGShop;
@interface XMGShopCell : UICollectionViewCell
@property (nonatomic, strong) XMGShop *shop;
@end

#import "XMGShopCell.h"
#import "XMGShop.h"
#import "UIImageView+WebCache.h"

@interface XMGShopCell()
@property (weak, nonatomic) IBOutlet UIImageView *imageView;
@property (weak, nonatomic) IBOutlet UILabel *priceLabel;
@end

@implementation XMGShopCell

- (void)setShop:(XMGShop *)shop
{
    _shop = shop;
    
    // 1.图片
    [self.imageView sd_setImageWithURL:[NSURL URLWithString:shop.img] placeholderImage:[UIImage imageNamed:@"loading"]];
    
    // 2.价格
    self.priceLabel.text = shop.price;
}
@end