iOS编程------集合视图UICollectionView

////  AppDelegate.h//  UI21_UICollectionView////  Created by l on 15/10/5.//  Copyright (c) 2015年 . All rights reserved.//#import <UIKit/UIKit.h>@interface AppDelegate : UIResponder <UIApplicationDelegate>@property (strong, nonatomic) UIWindow *window;@end////  AppDelegate.m//  UI21_UICollectionView////  Created by l on 15/10/5.//  Copyright (c) 2015年 . All rights reserved.//#import "AppDelegate.h"@interface AppDelegate ()@end@implementation AppDelegate- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    // Override point for customization after application launch.    return YES;}///////////////////////////////////////////////////////////////////////  ViewController.h//  UI21_UICollectionView////  Created by l on 15/10/5.//  Copyright (c) 2015年 . All rights reserved.//#import <UIKit/UIKit.h>@interface ViewController : UIViewController@end////  ViewController.m//  UI21_UICollectionView////  Created by l on 15/10/5.//  Copyright (c) 2015年 . All rights reserved.//#import "ViewController.h"#import "MyCollectionViewCell.h"#import "MyCollectionViewCell2.h"#define KCell @"mycell"#define KHeader @"header"#define KFooter @"footer"@interface ViewController ()<UICollectionViewDelegate, UICollectionViewDataSource> //创建collectionView遵守的两个协议,类似UITableView.@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];    /*    创建布局样式    UICollectionViewLayout, 为一个抽象类,我们通常使用它的子类,系统提供一个子类.    UICollectionViewLayout, 称为网格布局,对齐到网格.    */    //(1)创建布局对象    UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc] init];    //(2)配置布局对象    flowLayout.minimumLineSpacing = 10;                                    //行间距    flowLayout.minimumInteritemSpacing = 10;                               //列间距    CGFloat width = (self.view.bounds.size.width - 10 * 2 - 10 * 2) / 3;    CGFloat height = 2 * width;    flowLayout.itemSize = CGSizeMake(width, height);                        //单元格宽高    flowLayout.sectionInset = UIEdgeInsetsMake(10, 10, 10, 10);             //分区边距    flowLayout.scrollDirection = UICollectionViewScrollDirectionVertical;   //滚动方向    /*    注意:区头大小和区尾的宽高只有一个起作用,由混动方向决定.    如果是竖直滚动,宽度为集合视图宽度 collectionView.size.width,高度可以指定    如果是水平滚动,高度为集合视图高度,宽度可以指定.    */    flowLayout.headerReferenceSize = CGSizeMake(0, 100); //区头大小    flowLayout.footerReferenceSize = CGSizeMake(0, 50);  //区尾大小    /*    创建一个集合视图对象    集合视图不仅需要指定frame,还需要指定布局样式.    */    //(1)创建    UICollectionView *collectionView = [[UICollectionView alloc] initWithFrame:[UIScreen mainScreen].bounds collectionViewLayout:flowLayout];    //(2)设置delegate dataSource 等等.    collectionView.delegate = self;    collectionView.dataSource = self;    collectionView.backgroundColor = [UIColor redColor];    //(3)注册单元格,(区头, 区尾) 两种方式, 纯代码和xib    //单元格    [collectionView registerClass:[MyCollectionViewCell class] forCellWithReuseIdentifier:KCell];    //xib方式//    [collectionView registerNib:[UINib nibWithNibName:@"MyCollectionViewCell2" bundle:[NSBundle mainBundle]] forCellWithReuseIdentifier:@"cell"];    //区头    [collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:KHeader];    //区尾    [collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:KFooter];    //(4) 添加到父视图上    [self.view addSubview:collectionView];}#pragma mark---------- 实现协议里面的方法 -------------//分区中的元素数- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{    return 30;}//给元素加载单元格- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{    //1.从重用队列里面取    MyCollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:KCell forIndexPath:indexPath];    //2.配置单元格    //设置图片    cell.imageView.image = [UIImage imageNamed:@"image2.jpg"];    //设置label    cell.label.text = [NSString stringWithFormat:@"Sec:%ld Item:%ld", indexPath.section, indexPath.item];    //xib方式//    MyCollectionViewCell2 *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"cell" forIndexPath:indexPath];    //3.返回    return cell;}//加载区头,区尾- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath{    //根据kind去判断,加载的是区头还是区尾    if (kind == UICollectionElementKindSectionHeader) {        //(1)取出        UICollectionReusableView *headerView = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:KHeader forIndexPath:indexPath];        //(2)配置        headerView.backgroundColor = [UIColor yellowColor];        //(3)返回        return headerView;    } else {        //(1)取出        UICollectionReusableView *footerView = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:KFooter forIndexPath:indexPath];        //(2)配置        footerView.backgroundColor = [UIColor greenColor];        //(3)返回        return footerView;    }}//当单元格被选中的时候触发- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{    NSLog(@"分区号:%ld 元素下表:%ld", indexPath.section, indexPath.item);}- (void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}@end////////////////////////////////////////////////////////////////////////  MyCollectionViewCell.h//  UI21_UICollectionView////  Created by l on 15/10/5.//  Copyright (c) 2015年 . All rights reserved.//#import <UIKit/UIKit.h>@interface MyCollectionViewCell : UICollectionViewCell@property (nonatomic, strong, readonly) UIImageView *imageView; //显示图片@property (nonatomic, strong, readonly) UILabel *label;         //显示的label,展示分区号,item号@end////  MyCollectionViewCell.m//  UI21_UICollectionView////  Created by l on 15/10/5.//  Copyright (c) 2015年 . All rights reserved.//#import "MyCollectionViewCell.h"@implementation MyCollectionViewCell- (instancetype)initWithFrame:(CGRect)frame{    self = [super initWithFrame:frame];    if (self) {        _imageView = [[UIImageView alloc] initWithFrame:self.bounds];        [self.contentView addSubview:_imageView];        _label = [[UILabel alloc] initWithFrame:(CGRectMake(0, self.bounds.origin.y , self.bounds.size.width, 40))];        [self.contentView addSubview:_label];    }    return self;}@end///////////////////////////////////////////////////////////////////////  MyCollectionViewCell2.h//  UI21_UICollectionView////  Created by l on 15/10/5.//  Copyright (c) 2015年 . All rights reserved.//#import <UIKit/UIKit.h>@interface MyCollectionViewCell2 : UICollectionViewCell@property (strong, nonatomic) IBOutlet UIImageView *imageView;@end////  MyCollectionViewCell2.m//  UI21_UICollectionView////  Created by l on 15/10/5.//  Copyright (c) 2015年 . All rights reserved.//#import "MyCollectionViewCell2.h"@implementation MyCollectionViewCell2- (void)awakeFromNib {    // Initialization code}@end