collectionView怎么添加頭視圖

    我們要使用CollectionView里面的頭視圖需要先注冊頭視圖 UICollectionReusableView或者 繼承UICollectionReusableView的子類，kind類型為UICollectionElementKindSectionHeader，並且需要帶一個標識符，我們定義個static 的靜態字符串就行，如下所示：

 

 [collectionView registerClass:[UICollectionReusableViewclass ]   forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:headerViewIdentifier];

幾個重要的不能忽視的點就是  UICollectionViewFlowLayout 布局屬性需要設置 headerReferenceSize頭部的大小，不然頭視圖沒有大小不顯示；一定要在 

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath； 方法里面創建頭視圖view並給出frame，然后添加到  UICollectionReusableView 中。

詳細代碼如下

<pre name="code" class="objc">//
//  HomeViewController.m
//  collection添加頭部
//
//  Created by user on 15/10/10.
//  Copyright (c) 2015年 user. All rights reserved.
//

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


static NSString *headerViewIdentifier = @"hederview";

@interface HomeViewController ()<UICollectionViewDataSource,UICollectionViewDelegate>

@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];
    layout.minimumLineSpacing=20; //設置每一行的間距
    layout.itemSize=CGSizeMake(100, 100);  //設置每個單元格的大小
    layout.sectionInset=UIEdgeInsetsMake(0, 0, 50, 0);
    layout.headerReferenceSize=CGSizeMake(self.view.frame.size.width, 250); //設置collectionView頭視圖的大小

    UICollectionView *collectionView=[[UICollectionView alloc]initWithFrame:self.view.bounds collectionViewLayout:layout];
    collectionView.frame=self.view.bounds;
    //注冊cell單元格
   [collectionView registerNib:[UINib nibWithNibName:@"ConstomCell" bundle:nil] forCellWithReuseIdentifier:@"cell"];
    //注冊頭視圖
    [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 返回的單元格
-(UICollectionViewCell*)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    ConstomCell *cell=[collectionView dequeueReusableCellWithReuseIdentifier:@"cell" forIndexPath:indexPath];

    return cell;
}

//  返回頭視圖
- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
    //如果是頭視圖
    if ([kind isEqualToString:UICollectionElementKindSectionHeader]) {
         UICollectionReusableView *header=[collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:headerViewIdentifier forIndexPath:indexPath];
        //添加頭視圖的內容
        [self addContent];
        //頭視圖添加view
        [header addSubview:self.headerImage];
        return header;
    }
    //如果底部視圖
//    if([kind isEqualToString:UICollectionElementKindSectionFooter]){
//
//    }
    return nil;
}
/*
 *  補充頭部內容
 */
-(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