瀑布流.gif
基于完全自定義UICollectionViewLayout
#import "ViewController.h"
#import "GZDPhoto.h"
#import "GZDPhotoCell.h"
#import "GZDWaterFlowLayout.h"
//cellID
static NSString *const GZDCellID = @"photo";
@interface ViewController ()<UICollectionViewDataSource,GZDWaterFlowLayoutDelegate>
//將collectionView作為屬性
@property (weak,nonatomic) UICollectionView *collectionView;
/** 數(shù)據(jù)商品數(shù)組 */
@property (strong,nonatomic) NSMutableArray * photos;
@end
@implementation ViewController
#pragma mark - 懶加載
//圖片數(shù)組為從plist中加載
- (NSMutableArray *)photos {
if (!_photos) {
_photos =[GZDPhoto mj_objectArrayWithFile:[[NSBundle mainBundle] pathForResource:@"1.plist" ofType:nil]];
}
return _photos;
}
#pragma mark - 私有方法
- (void)viewDidLoad {
[super viewDidLoad];
//設(shè)置collectionView和做一些基本的配置
[self setupCollectionView];
//設(shè)置刷新控件,模擬下拉刷新和上拉加載更多
[self setupRefresh];
}
//設(shè)置collectionView
- (void)setupCollectionView {
//創(chuàng)建布局
#布局屬性完全繼承于UICollectionViewLayout基類
GZDWaterFlowLayout *layout = [[GZDWaterFlowLayout alloc] init];
//設(shè)置布局代理
layout.delegate = self;
//創(chuàng)建collectionView大小與控制器view的大小一致
UICollectionView *collectionView = [[UICollectionView alloc] initWithFrame:self.view.bounds collectionViewLayout:layout];
//設(shè)置背景顏色
collectionView.backgroundColor = [UIColor whiteColor];
//注冊自定義cell,cell為從xib中描述
[collectionView registerNib:[UINib nibWithNibName:NSStringFromClass([GZDPhotoCell class]) bundle:nil] forCellWithReuseIdentifier:GZDCellID];
//設(shè)置數(shù)據(jù)源
collectionView.dataSource = self;
[self.view addSubview:collectionView];
self.collectionView = collectionView;
}
#pragma mark - <UICollectionViewDataSource>
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
return self.photos.count;
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
GZDPhotoCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:GZDCellID forIndexPath:indexPath];
cell.photo = self.photos[indexPath.item];
return cell;
}
#pragma mark - <GZDWaterFlowLayoutDelegate>
## waterFlow代理方法 這個方法為@required 必須實(shí)現(xiàn),模型來源于控制器,所以控制器清楚每1個item的大小.
- (CGFloat)waterFlowLayout:(GZDWaterFlowLayout *)waterFlowLayout itemWidth:(CGFloat)itemWidth heightForItemAtIndexPath:(NSIndexPath *)indexPath {
GZDPhoto *photo = self.photos[indexPath.item];
//根據(jù)比例計算item的高度
return [photo.h floatValue] * itemWidth / [photo.w floatValue];
}
#@optional 方法返回布局一共有多少列
- (NSUInteger)numberOfColsInWaterFlowLayout:(GZDWaterFlowLayout *)layout {
return 3;
}
//控制四周cell與collectionView左右邊緣的距離
- (CGFloat)paddingInWaterFlowLayout:(GZDWaterFlowLayout *)layout {
return 20;
}
//控制cell之間的距離
- (CGFloat)marginInWaterFlowLayout:(GZDWaterFlowLayout *)layout {
return 30;
}
//控制cell四周的距離(主要是上下)
- (UIEdgeInsets)edgeInsetsInWaterFlowLayout:(GZDWaterFlowLayout *)layout {
return (UIEdgeInsets){5,10,20,40};
}
@end
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WaterFlowLayout.h文件
#import <UIKit/UIKit.h>
@class GZDWaterFlowLayout;
##模仿tableview 使用代理來設(shè)計接口,達(dá)到解耦和,從外界控制布局內(nèi)部的改變的目的
@protocol GZDWaterFlowLayoutDelegate <NSObject>
@required
#必須實(shí)現(xiàn)的方法,返回item的行高.
- (CGFloat)waterFlowLayout:(GZDWaterFlowLayout *)waterFlowLayout itemWidth:(CGFloat)itemWidth heightForItemAtIndexPath:(NSIndexPath *)indexPath;
@optional
//控制列數(shù)
- (NSUInteger)numberOfColsInWaterFlowLayout:(GZDWaterFlowLayout *)layout;
//控制padding
- (CGFloat)paddingInWaterFlowLayout:(GZDWaterFlowLayout *)layout;
//控制margin
- (CGFloat)marginInWaterFlowLayout:(GZDWaterFlowLayout *)layout;
//控制item四周間距
- (UIEdgeInsets)edgeInsetsInWaterFlowLayout:(GZDWaterFlowLayout *)layout;
@end
@interface GZDWaterFlowLayout : UICollectionViewLayout
@property (weak,nonatomic) id<GZDWaterFlowLayoutDelegate>
delegate;
@end
WaterFlowLayout.m文件
#import "GZDWaterFlowLayout.h"
/** 默認(rèn)的列數(shù) */
static CGFloat const GZDWaterFlowCols = 3;
/** 默認(rèn)的邊距 */
static CGFloat const GZDWaterFlowPadding = 10;
/** 默認(rèn)的邊距 */
static CGFloat const GZDWaterFolwMargin = 10;
/** 默認(rèn)的四邊距 */
static UIEdgeInsets const GZDWaterFlowEdgeInsets = {10,10,10,10};
@interface GZDWaterFlowLayout ()
/** 屬性數(shù)組 */
@property (strong,nonatomic) NSMutableArray * attributeses;
/** 行高數(shù)組 */
@property (strong,nonatomic) NSMutableArray * colHeights;
//getter方法聲明
- (NSUInteger)cols;
- (CGFloat)margin;
- (CGFloat)padding;
- (UIEdgeInsets)edgeInsets;
@end
@implementation GZDWaterFlowLayout
#pragma mark - getter方法實(shí)現(xiàn)
- (NSUInteger)cols {
if ([self.delegate respondsToSelector:@selector(numberOfColsInWaterFlowLayout:)]) {
return [self.delegate numberOfColsInWaterFlowLayout:self];
}else {
return GZDWaterFlowCols;
}
}
- (CGFloat)margin {
if ([self.delegate respondsToSelector:@selector(marginInWaterFlowLayout:)]) {
return [self.delegate marginInWaterFlowLayout:self];
}else {
return GZDWaterFolwMargin;
}
}
- (CGFloat)padding {
if ([self.delegate respondsToSelector:@selector(paddingInWaterFlowLayout:)]) {
return [self.delegate paddingInWaterFlowLayout:self];
}else {
return GZDWaterFlowPadding;
}
}
- (UIEdgeInsets)edgeInsets {
if ([self.delegate respondsToSelector:@selector(edgeInsetsInWaterFlowLayout:)]) {
return [self.delegate edgeInsetsInWaterFlowLayout:self];
}else {
return GZDWaterFlowEdgeInsets;
}
}
#pragma mark - 懶加載
- (NSMutableArray *)attributes {//屬性數(shù)組
if (!_attributeses) {
_attributeses = [NSMutableArray array];
}
return _attributeses;
}
- (NSMutableArray *)colHeights {//行高數(shù)組
if (!_colHeights) {
_colHeights = [NSMutableArray array];
}
return _colHeights;
}
/** 做一些準(zhǔn)備,在初始化的時候只會調(diào)一次,重新刷新時候會調(diào)用該方法 */
- (void)prepareLayout {
//一定要調(diào)super
[super prepareLayout];
//移除所有的行高元素,需要重新算一遍
[self.colHeights removeAllObjects];
//添加默認(rèn)的元素,即默認(rèn)行高是頂部的間距
for (NSInteger i = 0; i < self.cols; i++) {
[self.colHeights addObject:@(self.edgeInsets.top)];
}
//移除所有的布局元素
[self.attributeses removeAllObjects];
//只需要計算一次
for (NSInteger i = 0; i < [self.collectionView numberOfItemsInSection:0]; i++) {
//創(chuàng)建indexPath
NSIndexPath *indexPath = [NSIndexPath indexPathForItem:i inSection:0];
//創(chuàng)建indexPath處的布局元素
UICollectionViewLayoutAttributes *attributes = [self layoutAttributesForItemAtIndexPath:indexPath];
//添加進(jìn)布局元素數(shù)組
[self.attributeses addObject:attributes];
}
}
//返回布局元素數(shù)組,有多少個item就有多少個布局元素 --如果繼承自最初始的布局時 調(diào)用非常的頻繁,所以在prepareLayout方法中計算布局屬性
- (NSArray<UICollectionViewLayoutAttributes *> *)layoutAttributesForElementsInRect:(CGRect)rect {
return self.attributeses;
}
##返回indexPath位置的布局元素 -- 核心代碼
- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath {
UICollectionViewLayoutAttributes *attributes = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:indexPath];
//最短的那一行的行數(shù)
NSInteger minColNum = 0;
//最短的那一行的行高
CGFloat minColHeight = MAXFLOAT;
//遍歷行高數(shù)組
for (NSInteger i = 0; i < self.cols; i++) {
CGFloat colHeight = [self.colHeights[i] floatValue];
if (minColHeight > colHeight) {
minColHeight = colHeight;
minColNum = i;
}
}
CGFloat cellW = (self.collectionView.bounds.size.width - 2 * self.padding - (self.cols - 1) * self.margin) / self.cols;
//由于是必須實(shí)現(xiàn)的方法所以不需要判斷
CGFloat cellH = [self.delegate waterFlowLayout:self itemWidth:cellW heightForItemAtIndexPath:indexPath];
CGFloat cellY = minColHeight + self.edgeInsets.top;
CGFloat cellX = self.padding + minColNum * (self.margin + cellW);
attributes.frame = CGRectMake(cellX, cellY, cellW, cellH);
//更新行高數(shù)組
self.colHeights[minColNum] = @(CGRectGetMaxY(attributes.frame));
return attributes;
}
//返回contentSize
- (CGSize)collectionViewContentSize {
//遍歷取出最大的那一個行高
CGFloat maxHeight = [self.colHeights[0] floatValue];
for (NSInteger i = 1; i < self.colHeights.count; i++) {
CGFloat height = [self.colHeights[i] floatValue];
if (height > maxHeight) {
maxHeight = height;
}
}
return (CGSize){0,maxHeight + self.padding};
}
@end
