CollectionView

//集合视图

//创建全局静态重用标识符

static NSString * collectionID = @"id";

@interface ViewController ()

//代理

<UICollectionViewDelegate,UICollectionViewDataSource>

@end

@implementation ViewController

- (void)viewDidLoad {

[super viewDidLoad];

//特点一:创建CollectionView之前，先要创建CollectionView中的布局

UICollectionViewFlowLayout * layOut = [[UICollectionViewFlowLayout alloc]init];

//指定每个方格的尺寸

layOut.itemSize = CGSizeMake(310, 150);

//指定每个方格的边距 上、左、下、右

layOut.sectionInset = UIEdgeInsetsMake(10, 10, 10, 10);

//横向item最小间距

layOut.minimumInteritemSpacing = 0;

//设置纵向item最小间距

layOut.minimumLineSpacing = 10;

//更改CollectionView的滚动方向

//    layOut.scrollDirection = UICollectionViewScrollDirectionHorizontal;

//如果collectionView需要头尾视图则必须在layOut中指定头尾视图对应的尺寸

layOut.headerReferenceSize = CGSizeMake(320, 100);

UICollectionView * myCollectionView = [[UICollectionView alloc]initWithFrame:self.view.bounds collectionViewLayout:layOut];

//特点四：在使用CollectionView的时候，切记将CollectionView的背景颜色清空

myCollectionView.backgroundColor = [UIColor clearColor];

//在创建collectionView的时候，同时就要指定当前CollectionView中要使用的cell

[myCollectionView registerClass:[CustomCollectionViewCell class] forCellWithReuseIdentifier:collectionID];

//特点五：CollectionView的头尾视图

[myCollectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"HeaderView"];

myCollectionView.delegate = self;

myCollectionView.dataSource = self;

[self.view addSubview:myCollectionView];

}

-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section

{

return 24;

}

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath

{

//特点二:重用

CustomCollectionViewCell * cell = [collectionView dequeueReusableCellWithReuseIdentifier:collectionID forIndexPath:indexPath];

//    cell.backgroundColor = [UIColor redColor];

//特点三:collectionView的cell只有contentView

for (UIView * v in [cell.contentView subviews]) {

[v removeFromSuperview];

}

UILabel * label = [[UILabel alloc]initWithFrame:CGRectMake(0, 30, 100, 30)];

label.text = @"Cell";

[cell.contentView addSubview:label];

return cell;

}

//负责添加collectionView的头尾视图

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

{

UICollectionReusableView * RView = nil;

if ([kind isEqualToString:UICollectionElementKindSectionHeader]) {

//头视图

RView = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"HeaderView" forIndexPath:indexPath];

UIView * view = [[UIView alloc]initWithFrame:CGRectMake(0, 0, 320, 100)];

view.backgroundColor = [UIColor greenColor];

[RView addSubview:view];

}else{

}

return RView;

}

-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath

{

NSLog(@"%ld",indexPath.item);

}