iOS求生之路(四)UICollectionView的用法

////  ViewController.m//  UI1_UICollectionView////  Created by Fan_JinXin on 15/7/16.//  Copyright (c) 2015年 Fan_Jinxin. 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