UICollectionView

#import "ViewController.h"

@interfaceViewController ()<UICollectionViewDataSource,UICollectionViewDelegate,UICollectionViewDelegateFlowLayout>

@end

@implementation ViewController

- (void)viewDidLoad {

[superviewDidLoad];

UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayoutalloc] init];

UICollectionView *collection = [[UICollectionViewalloc] initWithFrame:self.view.boundscollectionViewLayout:layout];//初始化，并设置布局方式

collection.backgroundColor = [UIColor whiteColor];

[collection registerClass:[UICollectionViewCellclass] forCellWithReuseIdentifier:@"cell"];//注册UICollectionViewCell，这是固定格式，也是必须要实现的

[collection registerClass:[UICollectionReusableViewclass] forSupplementaryViewOfKind:UICollectionElementKindSectionHeaderwithReuseIdentifier:@"headerView"];//注册头/尾视图，视图类型必须为UICollectionReusableView或者其子类，kind设置为UICollectionElementKindSectionHeader或者UICollectionElementKindSectionFooter，最后设置标识

collection.delegate = self;

collection.dataSource = self;

[self.view addSubview:collection];

}

-(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView{

//设置组数，不写该方法默认是一组

return 4;

}

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

return 9;

}

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

staticNSString *identifier = @"cell";//注意，此处的identifier要与注册cell时使用的标识保持一致

UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];

cell.backgroundColor = [UIColor grayColor];

cell.layer.borderWidth = 0.5;

cell.layer.borderColor = [UIColorwhiteColor].CGColor;

return cell;

}

//设置头视图的尺寸，如果想要使用头视图，则必须实现该方法

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

return CGSizeMake(300, 30);

}

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

//根据类型以及标识获取注册过的头视图,注意重用机制导致的bug

UICollectionReusableView *headerView = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeaderwithReuseIdentifier:@"headerView"forIndexPath:indexPath];

headerView.backgroundColor = [UIColor brownColor];

for (UIView *view in headerView.subviews) {

[view removeFromSuperview];

}

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

label.text = [NSString stringWithFormat:@"%zi组的头视图",indexPath.section];

[headerView addSubview:label];

label.textColor = [UIColor whiteColor];

return headerView;

}

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

NSLog(@"%zi组，%zi行",indexPath.section,indexPath.item);

}

-(CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath{

//设置item尺寸

returnCGSizeMake(self.view.frame.size.width/3.0, 100);

}

-(UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section{

//设置组距离上向左右的间距

returnUIEdgeInsetsMake(0,0,0,0);

}

-(CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section{

//两个item的列间距

return 0;

}

-(CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section{

//如果一组中有多行item，设置行间距

return 0;

}

- (void)didReceiveMemoryWarning {

[superdidReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

@end