UICollectionView主要用于瀑布流，由于一直接触较少，每次需要使用的时候都从网上翻阅资料，此次自己总结整理，以备不时之需。
- collectionView和tableView最大的不同之处就是需要自定义cell,所以第一步自定义collectionViewCell
.h文件
#import <UIKit/UIKit.h>
@interface MyCollectionViewCell : UICollectionViewCell
@property (strong, nonatomic) UIImageView *topImage;
@property (strong, nonatomic) UILabel *botlabel;
@end
.m文件
#import "MyCollectionViewCell.h"
@implementation MyCollectionViewCell
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self)
{
_topImage = [[UIImageView alloc] initWithFrame:CGRectMake(10, 0, 70, 70)];
_topImage.backgroundColor = [UIColor redColor];
[self.contentView addSubview:_topImage];
_botlabel = [[UILabel alloc] initWithFrame:CGRectMake(10, 80, 70, 30)];
_botlabel.textAlignment = NSTextAlignmentCenter;
_botlabel.textColor = [UIColor blueColor];
_botlabel.font = [UIFont systemFontOfSize:15];
_botlabel.backgroundColor = [UIColor purpleColor];
[self.contentView addSubview:_botlabel];
}
return self;
}
@end
- 在viewController中实现collectionView的三个协议
UICollectionViewDataSource,UICollectionViewDelegate,UICollectionViewDelegateFlowLayout
- 具体实例化步骤均在代码中有注释，如下
#import "CollectionViewController.h"
#import "MyCollectionViewCell.h"
@interface CollectionViewController ()<UICollectionViewDataSource,UICollectionViewDelegate,UICollectionViewDelegateFlowLayout>
{
UICollectionView *mainCollectionView;
}
@end
@implementation CollectionViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
self.view.backgroundColor = [UIColor whiteColor];
//1.初始化layout
UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
//设置collectionView滚动方向
// [layout setScrollDirection:UICollectionViewScrollDirectionHorizontal];
//设置headerView的尺寸大小
layout.headerReferenceSize = CGSizeMake(self.view.frame.size.width, 100);
//该方法也可以设置itemSize
layout.itemSize =CGSizeMake(110, 150);
//2.初始化collectionView
mainCollectionView = [[UICollectionView alloc] initWithFrame:self.view.bounds collectionViewLayout:layout];
[self.view addSubview:mainCollectionView];
mainCollectionView.backgroundColor = [UIColor clearColor];
//3.注册collectionViewCell
//注意，此处的ReuseIdentifier 必须和 cellForItemAtIndexPath 方法中 一致 均为 cellId
[mainCollectionView registerClass:[MyCollectionViewCell class] forCellWithReuseIdentifier:@"cellId"];
//注册headerView 此处的ReuseIdentifier 必须和 cellForItemAtIndexPath 方法中 一致 均为reusableView
[mainCollectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"reusableView"];
//4.设置代理
mainCollectionView.delegate = self;
mainCollectionView.dataSource = self;
}
#pragma mark collectionView代理方法
//返回section个数
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
return 3;
}
//每个section的item个数
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
return 9;
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
MyCollectionViewCell *cell = (MyCollectionViewCell *)[collectionView dequeueReusableCellWithReuseIdentifier:@"cellId" forIndexPath:indexPath];
cell.botlabel.text = [NSString stringWithFormat:@"{%ld,%ld}",(long)indexPath.section,(long)indexPath.row];
cell.backgroundColor = [UIColor yellowColor];
return cell;
}
//设置每个item的尺寸
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{
return CGSizeMake(90, 130);
}
//footer的size
//- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section
//{
// return CGSizeMake(10, 10);
//}
//header的size
//- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section
//{
// return CGSizeMake(10, 10);
//}
//设置每个item的UIEdgeInsets
- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section
{
return UIEdgeInsetsMake(10, 10, 10, 10);
}
//设置每个item水平间距
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section
{
return 10;
}
//设置每个item垂直间距
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section
{
return 15;
}
//通过设置SupplementaryViewOfKind 来设置头部或者底部的view，其中 ReuseIdentifier 的值必须和 注册是填写的一致，本例都为 “reusableView”
- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
UICollectionReusableView *headerView = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"reusableView" forIndexPath:indexPath];
headerView.backgroundColor =[UIColor grayColor];
UILabel *label = [[UILabel alloc] initWithFrame:headerView.bounds];
label.text = @"这是collectionView的头部";
label.font = [UIFont systemFontOfSize:20];
[headerView addSubview:label];
return headerView;
}
//点击item方法
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
MyCollectionViewCell *cell = (MyCollectionViewCell *)[collectionView cellForItemAtIndexPath:indexPath];
NSString *msg = cell.botlabel.text;
NSLog(@"%@",msg);
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
/*
#pragma mark - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
// Get the new view controller using [segue destinationViewController].
// Pass the selected object to the new view controller.
}
*/
@end
完成以上两步，效果图如下：
demo.gif
