#import "ViewController.h"

#define ID @"reuse"

#import "MyCollectionViewCell.h"

#import "MyCollectionReusableView.h"

#define kWidth self.view.frame.size.width

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

@end

@implementation ViewController

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

    return CGSizeMake((kWidth - 40) / 3, 100);

}

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

    return UIEdgeInsetsMake(0, 0, 0, 0);

}

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

    return 20;

}

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

//    return 20;

//}

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

//    

//}

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

//    

//}

- (void)viewDidLoad {

    [super viewDidLoad];

    //创建一个布局对象，采用系统布局类UICollectionViewFlowLayout

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

    

//    //设置最小的行间距

//    layout.minimumLineSpacing = 10;

//    

//    //设置Item之间间距

//    layout.minimumInteritemSpacing = 10;

//    //设置集合视图的分区间隔

//    layout.sectionInset = UIEdgeInsetsMake(10, 10, 10, 10);

    //设置集合视图的滑动方向

    layout.scrollDirection = UICollectionViewScrollDirectionVertical;

    

    CGFloat totalWidth = self.view.frame.size.width;

    

    

    //设置每一个Item的尺寸大小

//    layout.itemSize = CGSizeMake((totalWidth - 40) / 3, 80);

    layout.headerReferenceSize = CGSizeMake(totalWidth, 40);

    

    //集合视图的创建必须指定布局，如果没有布局，显示不了任何东西

    UICollectionView *collectionView = [[UICollectionView alloc] initWithFrame:[UIScreen mainScreen].bounds collectionViewLayout:layout];

    

    //集合视图如果想要显示内容，必须将cell注册

    [collectionView registerClass:[MyCollectionViewCell class] forCellWithReuseIdentifier:ID];

    collectionView.dataSource = self;

    collectionView.delegate = self;

    

    //如果想要分区头视图显示，必须注册增广视图

    [collectionView registerClass:[MyCollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"header"];

    

    

    [self.view addSubview:collectionView];

    collectionView.backgroundColor = [UIColor grayColor];

    

    // Do any additional setup after loading the view, typically from a nib.

}

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

    return 60;

}

// The cell that is returned must be retrieved from a call to -dequeueReusableCellWithReuseIdentifier:forIndexPath:

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

//    static NSString *ID = @"reuse";

    MyCollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:ID forIndexPath:indexPath];

    

        cell.contentView.backgroundColor = [UIColor colorWithRed:arc4random() % 256 / 255.0 green:arc4random()  % 256 / 255.0 blue:arc4random() % 256 / 255.0 alpha:1.0];

    cell.numberLabel.text = [NSString stringWithFormat:@"道无涯第%ld步",indexPath.row + 1];

    return cell;

}

//设置分区个数

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

    return 3;

}

//返回增广视图，也就是集合视图的头视图或者尾视图

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

    MyCollectionReusableView *view = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"header" forIndexPath:indexPath];

    view.backgroundColor  = [UIColor blueColor];

    view.headerLabel.text = [NSString stringWithFormat:@"仙逆第%ld部 ",indexPath.section + 1];

    return view;

    

    

}

#pragma mark -----集合视图代理方法----

//Item点击之后触发的方法

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

    NSLog(@"%ld %ld",indexPath.section,indexPath.row);

}

#import "MyCollectionViewCell.h"

@implementation MyCollectionViewCell

- (instancetype)initWithFrame:(CGRect)frame {

    self = [super initWithFrame:frame];

    if (self) {

        //获取整体Item的宽和高

        CGFloat totalWidth = frame.size.width;

        CGFloat totalHeight = frame.size.height;

        self.numberLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 10, totalWidth, totalHeight - 20)];

        self.numberLabel.textAlignment = NSTextAlignmentCenter;

        self.numberLabel.font = [UIFont boldSystemFontOfSize:14];

        [self.contentView addSubview:self.numberLabel];

    }

    return self;

}

@end

#import "MyCollectionReusableView.h"

@implementation MyCollectionReusableView

- (instancetype)initWithFrame:(CGRect)frame {

    self = [super initWithFrame:frame];

    if (self) {

        self.headerLabel = [[UILabel alloc] initWithFrame:self.bounds];

        self.headerLabel.textAlignment = NSTextAlignmentCenter;

        self.headerLabel.font = [UIFont boldSystemFontOfSize:36];

        [self addSubview:self.headerLabel];

    }

    return self;

}

@end