Question

如何纯代码给UICollectionView添加HeaderView

Answer 1

UICollectionView主要用于瀑布流，由于一直接触较少，每次需要使用的时候都从网上翻阅资料，此次自己总结整理，以备不时之需。

collectionView和tableView最大的不同之处就是需要自定义cell,所以第一步自定义collectionViewCell

.h文件

#import <UIKit/UIKit.h>

@interface MyCollectionViewCell : UICollectionViewCell

@property (strong, nonatomic) UIImageView *topImage;

@property (strong, nonatomic) UILabel *botlabel;

@end

.m文件

#import "MyCollectionViewCell.h"

@implementation MyCollectionViewCell

- (id)initWithFrame:(CGRect)frame

{

self = [super initWithFrame:frame];

if (self)

{

_topImage = [[UIImageView alloc] initWithFrame:CGRectMake(10, 0, 70, 70)];

_topImage.backgroundColor = [UIColor redColor];

[self.contentView addSubview:_topImage];

_botlabel = [[UILabel alloc] initWithFrame:CGRectMake(10, 80, 70, 30)];

_botlabel.textAlignment = NSTextAlignmentCenter;

_botlabel.textColor = [UIColor blueColor];

_botlabel.font = [UIFont systemFontOfSize:15];

_botlabel.backgroundColor = [UIColor purpleColor];

[self.contentView addSubview:_botlabel];

}

return self;

}

@end

在viewController中实现collectionView的三个协议

UICollectionViewDataSource,UICollectionViewDelegate,UICollectionViewDelegateFlowLayout

具体实例化步骤均在代码中有注释，如下

#import "CollectionViewController.h"

#import "MyCollectionViewCell.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, 100);

//该方法也可以设置itemSize

layout.itemSize =CGSizeMake(110, 150);

//2.初始化collectionView

mainCollectionView = [[UICollectionView alloc成都软件开发公司http://www.yingtaow.com?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:[MyCollectionViewCell class] forCellWithReuseIdentifier:@"cellId"];

//注册headerView 此处的ReuseIdentifier 必须和 cellForItemAtIndexPath 方法中 一致 均为reusableView

[mainCollectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"reusableView"];

//4.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

{

MyCollectionViewCell *cell = (MyCollectionViewCell *)[collectionView dequeueReusableCellWithReuseIdentifier:@"cellId" forIndexPath:indexPath];

cell.botlabel.text = [NSString stringWithFormat:@"{%ld,%ld}",(long)indexPath.section,(long)indexPath.row];

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);

}

//footer的size

//- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section

//{

// return CGSizeMake(10, 10);

//}

//header的size

//- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section

//{

// return CGSizeMake(10, 10);

//}

//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”

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath

{

UICollectionReusableView *headerView = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"reusableView" forIndexPath:indexPath];

headerView.backgroundColor =[UIColor grayColor];

UILabel *label = [[UILabel alloc] initWithFrame:headerView.bounds];

label.text = @"这是collectionView的头部";

label.font = [UIFont systemFontOfSize:20];

[headerView addSubview:label];

return headerView;

}

//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.

}

/*

#pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {

// Get the new view controller using [segue destinationViewController].

// Pass the selected object to the new view controller.

}

*/

@end