UI1_UICollectionView

//  AppDelegate.m
//  UI1_UICollectionView
//
//  Created by zhangxueming on 15/7/16.
//  Copyright (c) 2015年 zhangxueming. All rights reserved.
//

#import "AppDelegate.h"
#import "ViewController.h"

@interface AppDelegate ()

@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Override point for customization after application launch.
    ViewController *root = [[ViewController alloc] init];
    UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:root];
    self.window.rootViewController = nav;
    self.window.backgroundColor = [UIColor whiteColor];

    return YES;
}

//  ViewController.h
//  UI1_UICollectionView
//
//  Created by zhangxueming on 15/7/16.
//  Copyright (c) 2015年 zhangxueming. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController

@end

//
//  ViewController.m
//  UI1_UICollectionView
//
//  Created by zhangxueming on 15/7/16.
//  Copyright (c) 2015年 zhangxueming. All rights reserved.
//

#import "ViewController.h"

//重用标志符
#define kCellReuseId @"cellId"

@interface ViewController () <UICollectionViewDataSource,UICollectionViewDelegate>
{
    UICollectionView *_collectionView;
    NSMutableArray *_dataList;
}

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    //1.创建数据源
    [self createDataList];
    //2.创建UI
    [self createCollectionView];
    //3.遵守协议,设置代理
}

//创建数据源
- (void)createDataList
{
    _dataList = [NSMutableArray array];
    for (int i=0; i<20; i++) {
        NSString *str = [NSString stringWithFormat:@"第%d个网格", i+1];
        [_dataList addObject:str];
    }
}

//创建UI

- (void)createCollectionView
{
    //第一个参数: collectionView 的位置
    //第二个参数: 布局对象, UICollectionViewLayout类(子类)的对象
    //规则布局
    //UICollectionViewFlowLayout:UICollectionViewLayout
    UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
    //上下左右边界的距离top, left, bottom, right
    layout.sectionInset  = UIEdgeInsetsMake(5, 5, 5, 5);
    //设置cell的大小
    layout.itemSize = CGSizeMake(180, 100);

    //设置横向的最小距离
    layout.minimumInteritemSpacing = 5;
    //设置竖向的最小距离
    layout.minimumLineSpacing = 10;

    _collectionView = [[UICollectionView alloc] initWithFrame:self.view.frame collectionViewLayout:layout];

    //设置代理
    _collectionView.delegate = self;
    _collectionView.dataSource  = self;

    //注册cell
    //第一个参数:cell的类型
    //第二个参数:cell的重用标识符
    [_collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:kCellReuseId];
    _collectionView.backgroundColor = [UIColor cyanColor];
    [self.view addSubview:_collectionView];
}

#pragma mark ---collectionView代理---

//返回分区的个数
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
    return 1;
}

//返回每个分区有多少个cell
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    return _dataList.count;
}

//返回cell

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    //UITableView : indexPath --> section row
    //UICollectionView: indexPath --> section item
    //从重用队列中取出cell
    UICollectionViewCell  *cell = [collectionView dequeueReusableCellWithReuseIdentifier:kCellReuseId forIndexPath:indexPath];

    cell.backgroundColor = [UIColor yellowColor];

    //移除cell.contentView 的子视图
    for (UIView *view in cell.contentView.subviews) {
        [view removeFromSuperview];
    }

    //在cell上显示内容
    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 30, 180, 40)];
    label.text = _dataList[indexPath.item];
    label.textAlignment = NSTextAlignmentCenter;
    [cell.contentView addSubview:label];

    return cell;
}

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

@end