UICollectionView(2)

ViewController.m

#import "ViewController.h"
#define MAS_SHORTHAND_GLOBALS
#import"Masonry.h"
static NSString *const identifier = @"cell";
@interface ViewController ()<UICollectionViewDataSource,UICollectionViewDelegate,UICollectionViewDelegateFlowLayout>
@property(nonatomic,strong)UICollectionView *cv;
@end

@implementation ViewController
#pragma make - flowlayout delegate 协议方法
//设置各分区不同的行距
-(CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section{
    if(section == 2 || section == 3){
        return 0;
    }
    return 10;
}
//设置各分区不同的项间距
-(CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section{
    if(section == 2 || section == 3){
        return 0;
    }
    return 10;
}
//设置不同分区的内边距
-(UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section{
    if(section == 2 || section == 3){
        return UIEdgeInsetsZero;
    }
    return UIEdgeInsetsMake(10, 10, 10, 10);
}
//设置不同分区项大小
-(CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath{
    switch (indexPath.section) {
        case 0:
            return CGSizeMake(20, 20) ;
        case 1:
            return CGSizeMake(80, 80) ;
        case 2:
            return CGSizeMake(180, 180) ;
        default:
            return CGSizeMake(50, 50);
    }
}
//设置不同的分区头视图的高度，如果高度设置为0，则表示没有分区头
-(CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section{
    switch (section) {
        case 0:
            return CGSizeMake(20, 20) ;
        case 1:
            return CGSizeMake(80, 80) ;
        case 2:
            return CGSizeMake(180, 180) ;
        default:
        return CGSizeMake(50, 50);}
}
//返回每个分区的 分区头 或分区脚的样式
-(UICollectionReusableView*)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath{
    //分区头复用
    if(kind == UICollectionElementKindSectionHeader){
    UICollectionReusableView *rv = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"headCell" forIndexPath:indexPath];
    rv.backgroundColor = [UIColor whiteColor];
    return rv;
    }
    //分区尾的复用
        UICollectionReusableView *fv = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:@"footerCell" forIndexPath:indexPath];
        fv.backgroundColor = [UIColor lightGrayColor];
        return fv;
}
-(UICollectionViewFlowLayout*)createLayoutObject{
    UICollectionViewFlowLayout *fLayout = [[UICollectionViewFlowLayout alloc]init];
    fLayout.minimumLineSpacing = 10;
    fLayout.minimumInteritemSpacing = 10;
    fLayout.sectionInset = UIEdgeInsetsMake(10, 20, 10, 20);
    CGFloat width = ([UIScreen mainScreen].bounds.size.width - 20*2 - 10*2)/3;
    fLayout.itemSize = CGSizeMake(width, width);
    //设置分区头高度
    fLayout.headerReferenceSize =CGSizeMake(0, 40);
    //设置分区脚高度
    fLayout.footerReferenceSize =CGSizeMake(0, 20);
    return fLayout;
}
-(UICollectionView *)cv{
    if(!_cv){
        _cv = [[UICollectionView alloc]initWithFrame:CGRectNull collectionViewLayout:[self createLayoutObject]];
        [self.view addSubview:_cv];
        _cv.dataSource = self;
        _cv.delegate = self;
        [_cv registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:identifier];
        //注册复用的分区头样式
        [_cv registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"headCell"];
        //注册复用的分区尾样式
        [_cv registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionFooter
       withReuseIdentifier:@"footerCell"];
        [_cv mas_makeConstraints:^(MASConstraintMaker *make) {
            make.edges.equalTo(UIEdgeInsetsMake(20, 0, 0, 0));
        }];
    }
    return _cv;
}
-(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView{
    return 4;
}
-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{
    switch (section) {
        case 0:
            return 6;
        case 1:
            return 12;
        case 3:
            return 8;
        default:
           return 18;
    }
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];
    cell.backgroundColor = [self randomColor];
    return cell;
}
- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    [self cv];
}
-(UIColor*)randomColor{
    CGFloat red = (arc4random()%256) /255.0;
    CGFloat green = (arc4random()%256) /255.0;
    CGFloat blue = (arc4random()%256) / 255.0;
    return [UIColor colorWithRed:red green:green blue:blue alpha:1];
}