UICollectionView实现分组显示

准备工作

1,新建xib，删除画布上的view对象，并从库中拖入Collect View Header View

2,打开该对象的attribute inspector设置重用id

3，新建一个类，继承自UICollectionReusableView，并将xib中custome类设置为刚才新建的类

@interface ElectiveCourse :UIViewController
{
   BOOL                     _isLoading;
   NSMutableArray           *_dataArray;
   NSMutableDictionary      *_coursePackDic;
}
@property(nonatomic,strong)UICollectionView         *collectionView;

//-----
- (AppDelegate *)appdelegate;
-(void)refreshCoursePackData:(NSInteger)courseId;
- (instancetype) initCollectionView;
@end

//
//  ElectiveCourse.m
//  LearningEnglish
//
//  Created by Xu Felicia on 14-5-15.
//  Copyright (c) 2014年 xxx.com. All rights reserved.
//

#import "ElectiveCourse.h"
#import "subjectItem.h"
#import "studyWordController.h"
#import "MJRefresh.h"
#import "MeController.h"
#import "CollectViewHeaderView.h"

@interface ElectiveCourse ()

@end

@implementation ElectiveCourse

static NSString *strCellIdentify =@"subjectItemIdentify";

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
   self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
   if (self) {
       self.title =@"选课";
    }
    return self;
}


static NSString *kCollectionViewHeaderIdentifier =@"cccc";


//
- (UICollectionViewFlowLayout *) flowLayout{
    UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc] init];

    UICollectionViewFlowLayout *layout  = [[UICollectionViewFlowLayout alloc] init];
    layout.scrollDirection              = UICollectionViewScrollDirectionVertical;

   if (iPhone5)
    {
        layout.itemSize                     = CGSizeMake(100, 100);
        layout.minimumInteritemSpacing      = 20;
        layout.minimumLineSpacing           = 40;
        layout.sectionInset                 = UIEdgeInsetsMake( 20, 40, 20, 40);
        
    }else
    {
        layout.itemSize                     = CGSizeMake(100, 100);
        layout.minimumInteritemSpacing      = 20;
        layout.minimumLineSpacing           = 20;
        layout.sectionInset                 = UIEdgeInsetsMake( 20, 40, 20, 40);
    }

   return layout;
}

//最初一直没实现如下方法，导致莫名其妙的错误
-(CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section
{
   return CGSizeMake(320, 20);
}


- (void)addHeader
{

    __unsafe_unretainedtypeof(self) vc =self;
    //添加下拉刷新头部控件
    [self.collectionView addHeaderWithCallback:^{
        // 进入刷新状态就会回调这个Block
        
        //模拟延迟加载数据，因此2秒后才调用）
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            [vc.collectionView reloadData];
           //结束刷新
            [vc.collectionView headerEndRefreshing];
        });
    }];
}


-(void)queryCourseData
{
     [self refreshCoursePackData:1];
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    UIView *topNavView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, ScreenWidth, 20)];
    topNavView.backgroundColor = [UIColor colorWithRed:33/255.0 green:169/255.0 blue:186/255.0 alpha:1];
    [self.view addSubview:topNavView];
    
    
   self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:@"r"] style:UIBarButtonItemStyleDone target:self action:@selector(showLeftView)];
    
    NSString *strPath                   = [[NSBundle mainBundle] pathForResource:@"Home" ofType:@"plist"];
    _coursePackDic                      = [NSDictionary dictionaryWithContentsOfFile:strPath];
    
 
    
    UICollectionViewFlowLayout *layout  = [[UICollectionViewFlowLayout alloc] init];
    layout.scrollDirection              = UICollectionViewScrollDirectionVertical;
   
   if (iPhone5)
    {
        layout.itemSize                     = CGSizeMake(100, 100);
        layout.minimumInteritemSpacing      = 6;
        layout.minimumLineSpacing           = 6;
        
        layout.sectionInset                 = UIEdgeInsetsMake( 3, 40, 3, 40);
        
    }else
    {
        layout.itemSize                     = CGSizeMake(100, 100);
        layout.minimumInteritemSpacing      = 6;
        layout.minimumLineSpacing           = 6;
        layout.sectionInset                 = UIEdgeInsetsMake( 3, 40, 3, 40);
    }

   self.collectionView                       = [[UICollectionView alloc] initWithFrame:CGRectMake(0, 64, 320, ScreenHeight -40) collectionViewLayout:layout];
   self.collectionView.collectionViewLayout = layout;

   self.collectionView.alwaysBounceVertical  =YES;
   self.collectionView.backgroundColor       = [UIColor groupTableViewBackgroundColor];
   self.collectionView.dataSource            =self;
   self.collectionView.delegate              =self;
    
    [self.collectionView registerClass:[subjectItem class] forCellWithReuseIdentifier:strCellIdentify];
    
    
    UINib *headerNib = [UINib nibWithNibName:NSStringFromClass([CollectViewHeaderView class])  bundle:[NSBundle mainBundle]];
    [self.collectionView registerNib:headerNib  forSupplementaryViewOfKind :UICollectionElementKindSectionHeader  withReuseIdentifier: kCollectionViewHeaderIdentifier ];  //注册加载头
    
    [self.view addSubview:self.collectionView];
    
    [self queryCourseData];

    [self addHeader];
//  [self addFooter];
    
}


//
-(void)refreshCoursePackData:(NSInteger)courseId
{
    NSString *skey = [NSStringstringWithFormat:@"p%d",courseId];
    NSMutableDictionary *dic =_coursePackDic[skey];
    _dataArray = [dicobjectForKey:@"data"];
   self.title = dic[@"title"];
    [self.collectionViewreloadData];
    
}


-(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
    return_dataArray.count;
}

-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
   NSArray *arr =_dataArray[section][@"courses"];
   return arr.count;
}


-(UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
    CollectViewHeaderView *view = [collectionViewdequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeaderwithReuseIdentifier:@"cccc"forIndexPath:indexPath];
 
    view.title = [NSString stringWithFormat:@"——%@——",_dataArray[indexPath.section][@"title"]];
   return view;
}

-(UICollectionViewCell*)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    subjectItem *cell       = [collectionView dequeueReusableCellWithReuseIdentifier:strCellIdentify forIndexPath:indexPath];

   /*
    NSDictionary *dic       = _dataArray[indexPath.row];
    [cell initWithDic:dic];
 
    int idx = [[dic objectForKey:@"imgidx"] intValue];
    int64_t nId = 100002 + idx * 3;
     */
    
    int64_t nId = 100002 + (arc4random() % 100 * 3);
    
    NSString *strURL        = [NSString stringWithFormat:@"http://lingo7.oss-cn-hangzhou.aliyuncs.com/images/%lld.jpg",nId];
    NSURL *url              = [NSURL URLWithString:strURL];
    [cell.imageView setImageWithURL:url placeholderImage:[UIImage imageNamed:@"image_home_replace"]];
    
    cell.imageFlag.image = (cell.data.flag == 0?nil:[UIImage imageNamed:@"image_home_selflag"]);;

    
   return cell;
}
@end

运行效果如下