https://www.cnblogs.com/xubaoaichiyu/p/5294382.html
UICollectionView在众多控件中也算是比较常用的了，像淘宝在浏览宝贝时采用的就是UICollectionView，对于UICollectionView－>UICollectionViewFlowLayout当然也是必不可少的了，还是老样子结合代码进行简单介绍，首先看一下UICollectionView实现结果：
实现这些功能很简单，代码量极少，线看一下代码，然后进行深入了解：
//
// ViewController.m
// CX－UICollentionVIew基础
//
// Created by ma c on 16/3/19.
// Copyright © 2016年 xubaoaichiyu. All rights reserved.
//
#import "ViewController.h"
static NSString * identifier = @"cxCellID";
@interface ViewController ()<UICollectionViewDataSource>
@property (nonatomic, strong) UICollectionView * collectionView;
@end
@implementation ViewController
#pragma mark - set_and_get
-(UICollectionView *)collectionView{
if (!_collectionView) {
//自动网格布局
UICollectionViewFlowLayout * flowLayout = [[UICollectionViewFlowLayout alloc]init];
//网格布局
_collectionView = [[UICollectionView alloc]initWithFrame:self.view.frame collectionViewLayout:flowLayout];
//注册cell
[_collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:identifier];
//设置数据源代理
_collectionView.dataSource = self;
}
return _collectionView;
}
#pragma mark - life
- (void)viewDidLoad {
[super viewDidLoad];
[self.view addSubview:self.collectionView];
}
#pragma mark - deleDate
//有多少的分组
-(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView{
return 2;
}
//每个分组里有多少个item
-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{
return 100;
}
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
//根据identifier从缓冲池里去出cell
UICollectionViewCell * cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];
cell.backgroundColor = [UIColor orangeColor];
return cell;
}
@end
介绍过最最基本的知识点之后，按着步骤来，进行进一步介绍。
UICollectionViewFlowLayout的使用让UICollectionView更加丰富多彩，下面看一下使用UICollectionViewFlowLayout之后的效果吧－>
代码－>
//
// ViewController.m
// CX－UICollentionVIew基础
//
// Created by ma c on 16/3/19.
// Copyright © 2016年 xubaoaichiyu. All rights reserved.
//
#import "ViewController.h"
static NSString * identifier = @"cxCellID";
static CGFloat kMagin = 10.f;
static NSString * headIdentifier = @"cxHeadID";
@interface ViewController ()<UICollectionViewDataSource>
@property (nonatomic, strong) UICollectionView * collectionView;
@end
@implementation ViewController
#pragma mark - set_and_get
-(UICollectionView *)collectionView{
if (!_collectionView) {
//自动网格布局
UICollectionViewFlowLayout * flowLayout = [[UICollectionViewFlowLayout alloc]init];
CGFloat itemWidth = (self.view.frame.size.width - 4 * kMagin) / 3;
//设置单元格大小
flowLayout.itemSize = CGSizeMake(itemWidth, itemWidth / 0.618);
//最小行间距(默认为10)
flowLayout.minimumLineSpacing = 10;
//最小item间距（默认为10）
flowLayout.minimumInteritemSpacing = 10;
//设置senction的内边距
flowLayout.sectionInset = UIEdgeInsetsMake(kMagin, kMagin, kMagin, kMagin);
//设置UICollectionView的滑动方向
flowLayout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
//sectionHeader的大小,如果是竖向滚动，只需设置Y值。如果是横向，只需设置X值。
flowLayout.headerReferenceSize = CGSizeMake(100,0);
//网格布局
_collectionView = [[UICollectionView alloc]initWithFrame:self.view.frame collectionViewLayout:flowLayout];
//注册cell
[_collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:identifier];
//注册header
[_collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:headIdentifier];
//设置数据源代理
_collectionView.dataSource = self;
}
return _collectionView;
}
#pragma mark - life
- (void)viewDidLoad {
[super viewDidLoad];
[self.view addSubview:self.collectionView];
}
#pragma mark - deleDate
//有多少的分组
-(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView{
return 2;
}
//每个分组里有多少个item
-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{
return 100;
}
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
//根据identifier从缓冲池里去出cell
UICollectionViewCell * cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];
cell.backgroundColor = [UIColor orangeColor];
return cell;
}
-(UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath{
//kind有两种 一种时header 一种事footer
if (kind == UICollectionElementKindSectionHeader) {
UICollectionReusableView * header = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:headIdentifier forIndexPath:indexPath];
header.backgroundColor = [UIColor yellowColor];
return header;
}
return nil;
}
@end
灵活的是使用 UICollectionView＋UICollectionViewFlowLayout 会带来更多的有趣的体验，随后我会介绍一些比较实用的实现。