iOS的UICollectionView添加header

#import "HomeViewController.h"
#import "ConstomCell.h"

static NSString *headerViewIdentifier = @"hederview";

@interface HomeViewController ()<UICollectionViewDataSource,UICollectionViewDelegate，UICollectionViewDelegateFlowLayout>

@property (nonatomic,strong) UIImageView *headerImage;
@end

@implementation HomeViewController

- (void)viewDidLoad {
[super viewDidLoad];
//1.添加collectionview
[self addCollectionView];
}

-(void)addCollectionView
{
UICollectionViewFlowLayout *layout=[[UICollectionViewFlowLayout alloc]init];
//设置每一行的间距
layout.minimumLineSpacing=20;
//设置每个单元格的大小   layout.itemSize=CGSizeMake(100, 100);
layout.sectionInset=UIEdgeInsetsMake(0, 0, 50, 0);
//设置collectionView头视图的大小  layout.headerReferenceSize=CGSizeMake(self.view.frame.size.width, 250);

UICollectionView *collectionView=[[UICollectionView alloc]initWithFrame:self.view.bounds collectionViewLayout:layout];
collectionView.frame=self.view.bounds;
//注册cell单元格
[collectionView registerNib:[UINib nibWithNibName:@"ConstomCell" bundle:nil] forCellWithReuseIdentifier:@"cell"];
//注册头视图
[collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:headerViewIdentifier];
collectionView.backgroundColor=[UIColor whiteColor];
collectionView.delegate=self;
collectionView.dataSource=self;
[self.view addSubview:collectionView];
}

#pragma mark  返回多少行
-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
return 13;
}
#pragma markk 返回的单元格
-(UICollectionViewCell*)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
ConstomCell *cell=[collectionView dequeueReusableCellWithReuseIdentifier:@"cell" forIndexPath:indexPath];
return cell;
}

//  返回头视图
- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
//如果是头视图
if ([kind isEqualToString:UICollectionElementKindSectionHeader]) {
UICollectionReusableView *header=[collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:headerViewIdentifier forIndexPath:indexPath];
//添加头视图的内容
[self addContent];
//头视图添加view
[header addSubview:self.headerImage];
return header;
}
//如果底部视图
//    if([kind isEqualToString:UICollectionElementKindSectionFooter]){
//    }
return nil;
}

/*
*  补充头部内容
*/
-(void)addContent
{
UIImageView *headerImage=[[UIImageView alloc]init];
headerImage.contentMode=UIViewContentModeScaleAspectFill;
headerImage.clipsToBounds=YES;
headerImage.frame=CGRectMake(0, 0, self.view.frame.size.width, 250);
headerImage.image=[UIImage imageNamed:@"mei"];
self.headerImage=headerImage;
}

@end