代码创建UICollectionView（带分组header）

1，在viewController中实现collectionView的三个协议

<UICollectionViewDataSource,UICollectionViewDelegate,UICollectionViewDelegateFlowLayout>

2,创建cell

//.h#import <UIKit/UIKit.h>#import "ListModel.h"@interface AppListCollectCell : UICollectionViewCell@property (nonatomic,strong) ListModel *listModel;@property (nonatomic,strong) UIImageView *imageV;@property (nonatomic,strong) UILabel *lab;@end

//.m#import "AppListCollectCell.h"@implementation AppListCollectCell-(instancetype)initWithFrame:(CGRect)frame{    if (self=[super initWithFrame: frame]) {        _imageV=[[UIImageView alloc] init];_imageV.contentMode=UIViewContentModeScaleAspectFill;        _imageV.layer.cornerRadius=22.5;        _imageV.clipsToBounds=YES;        [self addSubview:_imageV];        _lab = [[UILabel alloc] init];        _lab.font = H_FONT12;        if (ScreenWidth == 320) {            _lab.font = H_FONT11;        }        _lab.textColor = H_BLACKTEXTCOLOR;        _lab.textAlignment=NSTextAlignmentCenter;        [self addSubview:_lab];        [_imageV mas_makeConstraints:^(MASConstraintMaker *make) {            make.top.equalTo (self.mas_top).mas_offset(0);            make.width.mas_equalTo(45);            make.height.mas_equalTo(45);        }];        [_lab mas_makeConstraints:^(MASConstraintMaker *make) {            make.top.equalTo (_imageV.mas_bottom).mas_offset(12);            make.left.equalTo (self.mas_left).mas_offset(-18);            make.right.equalTo (self.mas_right).mas_offset(18);            make.height.mas_equalTo(14);        }];    }    return self;}- (void)setListModel:(AppListModel *)listModel{    [_imageV sd_setImageWithURL:[NSURL URLWithString:listModel.avatar] placeholderImage:[UIImage imageNamed:H_HOMEPLACE]];    _listModel = listModel;    _lab.text = listModel.name;}

3,创建headerView

//.h#import <UIKit/UIKit.h>@interface HomeCollectionHeader : UICollectionReusableView@property (nonatomic,strong) UILabel *headeLab;@end

#import "HomeCollectionHeader.h"@implementation HomeCollectionHeader- (instancetype)initWithFrame:(CGRect)frame{    if (self = [super initWithFrame:frame]) {        [self createSubViews];    }    return self;}- (void)createSubViews{    UIView *lineView = [UIView new];    lineView.backgroundColor = H_LINECOLOR;    lineView.frame = CGRectMake(0, 0, ScreenWidth, 0.5);    [self addSubview:lineView];    self.headeLab = [UILabel new];    self.headeLab.frame = CGRectMake(20, 25, 300, 14);    self.headeLab.font = H_FONTCONTENTNAME;    self.headeLab.textColor = H_GRAYTEXTCOLOR;    [self addSubview:self.headeLab];}@end

4,viewController

这里写代码片

#import "CollectionViewController.h"#import "HomeCollectionHeader.h"#import "AppListCollectCell.h"@interface CollectionViewController ()<UICollectionViewDataSource,UICollectionViewDelegate,UICollectionViewDelegateFlowLayout>{    UICollectionView *mainCollectionView;}@end@implementation CollectionViewController- (void)viewDidLoad {    [super viewDidLoad];    // Do any additional setup after loading the view.    self.view.backgroundColor = [UIColor whiteColor];    //1.初始化layout    UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];    //设置collectionView滚动方向//    [layout setScrollDirection:UICollectionViewScrollDirectionHorizontal];    //设置headerView的尺寸大小    layout.headerReferenceSize = CGSizeMake(self.view.frame.size.width, 40);    //该方法也可以设置itemSize    layout.itemSize =CGSizeMake(110, 150);    //2.初始化collectionView    mainCollectionView = [[UICollectionView alloc] initWithFrame:self.view.bounds collectionViewLayout:layout];    [self.view addSubview:mainCollectionView];    mainCollectionView.backgroundColor = [UIColor clearColor];    //3.注册collectionViewCell    //注意，此处的ReuseIdentifier 必须和 cellForItemAtIndexPath 方法中 一致 均为 cellId    [mainCollectionView registerClass:[AppListCollectCell class] forCellWithReuseIdentifier:@"cellId"];    //注册headerView  此处的ReuseIdentifier 必须和 cellForItemAtIndexPath 方法中 一致  均为reusableView    [mainCollectionView registerClass:[HomeCollectionHeader class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"reusableView"];    //设置代理    mainCollectionView.delegate = self;    mainCollectionView.dataSource = self;}#pragma mark collectionView代理方法//返回section个数- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView{    return 3;}//每个section的item个数- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{    return 9;}- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{    AppListCollectCell *cell =[collectionView dequeueReusableCellWithReuseIdentifier:@"cellId" forIndexPath:indexPath];    cell.backgroundColor = [UIColor yellowColor];    return cell;}//设置每个item的尺寸- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath{    return CGSizeMake(90, 130);}//header的size-(CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section{    return CGSizeMake(ScreenWidth, 40);}//设置每个item的UIEdgeInsets- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section{    return UIEdgeInsetsMake(10, 10, 10, 10);}//设置每个item水平间距- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section{    return 10;}//设置每个item垂直间距- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section{    return 15;}//通过设置SupplementaryViewOfKind 来设置头部或者底部的view，其中 ReuseIdentifier 的值必须和 注册是填写的一致，本例都为 “reusableView”#pragma mark -- 返回头视图- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath{    UICollectionReusableView *reusableView = nil;        if ([kind isEqualToString:UICollectionElementKindSectionHeader]) {        HomeCollectionHeader *header = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"offlineID" forIndexPath:indexPath];            header.headeLab.text = [dict objectForSafeKey:@"组头"];        reusableView = header;    }    //如果是头视图    return reusableView;}//点击item方法- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{    MyCollectionViewCell *cell = (MyCollectionViewCell *)[collectionView cellForItemAtIndexPath:indexPath];    NSString *msg = cell.botlabel.text;    NSLog(@"%@",msg);}- (void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}