UICollectionView Demo

闲来无事….写个UICollectionView Demo

////  ViewController.m//  CollectionViewDemo////  Created by 赵伟争 on 2016/11/3.//  Copyright © 2016年 zwz. All rights reserved.//#import "ViewController.h"@interface ViewController ()<UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout>{    UICollectionViewFlowLayout *_customLayout;    UICollectionView *_collectionView;    BOOL isLogin; //YES: 登录, NO: 不是}@endstatic NSString *cellIdentifier = @"CELL";static NSString *headerIdentifier = @"header";static NSString *footIdentifier = @"foot";@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];    isLogin = YES; //判断是否登录,手动设置,  或者登录后设置, 刷新整个CollectionView    UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];    //滚动方向    layout.scrollDirection = UICollectionViewScrollDirectionVertical;    UICollectionView *collectionView = [[UICollectionView alloc] initWithFrame:self.view.frame collectionViewLayout:layout];    collectionView.backgroundColor = [UIColor whiteColor];    collectionView.dataSource = self;    collectionView.delegate = self;    //UICollectionViewCell 可以自定义    [collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:cellIdentifier];    //[collectionView registerClass:[ChoosePictureHeader class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:headerIdentifier];    //[collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:footIdentifier];    [self.view addSubview:collectionView];    // Do any additional setup after loading the view, typically from a nib.}#pragma mark - UICollectionView数据源// 返回有多少个cell- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{    if (section == 0) {        if (isLogin) {            return 4;        } else {            return 8;        }    } else {        return 8;    }    //    return 30;}- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView;{    if (isLogin) {        return 2;    } else {        return 1;    }}// 返回每个cell长什么样子- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{    //可以自定义UICollectionViewCell    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:cellIdentifier forIndexPath:indexPath];    cell.backgroundColor = [UIColor redColor];    return cell;}- (void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}//设置item的大小- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {    CGFloat width = [UIScreen mainScreen].bounds.size.width;    if (indexPath.section == 0) {        if (isLogin) {            CGFloat oneSectionWidth = width/2;            return CGSizeMake(oneSectionWidth-1.5, oneSectionWidth/2);        } else {            CGFloat oneSectionWidth = width/4;            return CGSizeMake(oneSectionWidth-1.5, oneSectionWidth-1.2);        }    } else {        CGFloat oneSectionWidth = width/4;        return CGSizeMake(oneSectionWidth-1.5, oneSectionWidth-1.2);    }}//UIEdgeInsetsMake(CGFloat top, CGFloat left, CGFloat bottom, CGFloat right)- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section {    return UIEdgeInsetsMake(15, 1, 5, 1);}//最小行间距- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section {    return 1.0f;}//item之间的最小距离- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section {    return 1.0f;}@end