在iOS6.0之後，蘋果推出了?個新的繼承於UIScrolleriew的一個視 圖，UICollectionView，也被稱之為集合視圖。和UITableView共同作為 在開發中常常用的兩個視圖，常常作為項目的主界面出現。

　　代碼演示：

#import "YourCollectionViewCell.h"

@implementation YourCollectionViewCell
-(instancetype)initWithFrame:(CGRect)frame{
    self = [super initWithFrame:frame];
    if (self) {
        //獲取整體item的寬和高
        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:36];
        [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




#import "ViewController.h"
#import "YourCollectionViewCell.h"
#import "MyCollectionReusableView.h"
#define kReuse @"reuse"
#define kWidth self.view.frame.size.width
@interface ViewController ()

@end


@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    //創建一個布局對象，采用系統布局類UICollectionViewFlowLayout
 
    UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc]init];
    /*
    //設置最小行間距
    layout.minimumLineSpacing = 20;
    //設置item與item之間的間距
    layout.minimumInteritemSpacing = 10;
    layout.sectionInset = UIEdgeInsetsMake(10, 10, 10, 10);
    //設置每一個item的尺寸
    CGFloat totalWidth = self.view.frame.size.width;
    layout.itemSize = CGSizeMake((totalWidth - 40)/3, 80);
    */
    //設置滑動方向
    layout.scrollDirection = UICollectionViewScrollDirectionVertical;
    //集合視圖的創建必須指定布局，如果沒有布局，顯示不了任何東西
    UICollectionView *collectionView = [[UICollectionView alloc]initWithFrame:[[UIScreen mainScreen]bounds] collectionViewLayout:layout];
    collectionView.dataSource = self;
    collectionView.delegate = self;
    //集合視圖如果想要顯示內容，必須要將cell進行注冊
    [collectionView registerClass:[YourCollectionViewCell class] forCellWithReuseIdentifier:kReuse];
    //集合視圖如果想要分區頭視圖顯示 ，必須注冊增廣視圖
    [collectionView registerClass:[MyCollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"header"];
    //給頭視圖布局
    layout.headerReferenceSize = CGSizeMake(kWidth, 40);
    
    [self.view addSubview:collectionView];
    
    
}

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath{
    return CGSizeMake((kWidth - 40)/3, 80);
}
- (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;
//}


- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}



#pragma mark -------集合視圖數據源協議-------
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{
    return 15;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
    
    YourCollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:kReuse 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:@"%ld",indexPath.row];
    return cell;
}
//返回增廣視圖，也就是集合視圖的頭視圖或者尾視圖
-(UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath{
    MyCollectionReusableView *view = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"header" forIndexPath:indexPath];
    view.headerLabel.text = [NSString stringWithFormat:@"當前分區為:%ld",indexPath.section];
    view.backgroundColor = [UIColor yellowColor];
    return view;
}

//設置分區個數
-(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView{
    return 10;
}

#pragma mark -------集合視圖代理方法-----

-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{
    NSLog(@"%ld,%ld",indexPath.section,indexPath.row);
}

@end