1. 自定义流布局继承自UICollectionViewFlowLayout

import <UIKit/UIKit.h>

@interface YHPPictrueChoicesFlowLayout : UICollectionViewFlowLayout
@end

import "YHPPictrueChoicesFlowLayout.h"

@implementation YHPPictrueChoicesFlowLayout
/** 在 collectionView 第一次布局的时候调用，此时 collectionView 的 frame 已经设置完毕 */

• (void)prepareLayout {
  // 一定 super
  [super prepareLayout];
  /** item大小 /
  self.itemSize = CGSizeMake(50, 50);
  /* 列间距 /
  self.minimumInteritemSpacing = 10;
  /* 行间距 /
  self.minimumLineSpacing = 10;
  /* 滚动方向 /
  self.scrollDirection = UICollectionViewScrollDirectionVertical;
  /* 弹簧效果 /
  self.collectionView.bounces = NO;
  /* 分页 /
  self.collectionView.pagingEnabled = YES;
  /* 水平滚动指示条 /
  self.collectionView.showsHorizontalScrollIndicator = NO;
  /* 垂直滚动指示条 */
  self.collectionView.showsVerticalScrollIndicator = NO;
  }

2. 自定义cell

import <UIKit/UIKit.h>

@interface YHPPictureChoiceCell : UICollectionViewCell
@end

import "YHPPictureChoiceCell.h"

@implementation YHPPictureChoiceCell
// collectionViewCell 的 frame 是根据之前的 layout 已经确定好的！

• (instancetype)initWithFrame:(CGRect)frame {
  self = [super initWithFrame:frame];
  if (self) {
  /** 添加子控件 */
  }
  return self;
  }
  @end
  3.YHPPictureChoiceController

import <UIKit/UIKit.h>

@interface YHPPictureChoiceController : UICollectionViewController
@end

import "YHPPictureChoiceController.h"

import "YHPPictrueChoicesFlowLayout.h"

import "YHPPictureChoiceCell.h"

@interface YHPPictureChoiceController ()
/** 自定义流布局 /
@property (nonatomic, strong) YHPPictrueChoicesFlowLayout layout;
@property (nonatomic, strong) YHPPictureChoiceCell cell;
@end
@implementation YHPPictureChoiceController
/ 注册cell重用标识 /
static NSString * YHPPICTURECHOICECELL = @"YHPPictureChoiceCell";
/ 懒加载cell /
-(YHPPictureChoiceCell )cell {
if (_cell == nil) {
_cell = [[YHPPictureChoiceCell alloc]init];
}
return _cell;
}
/ 懒加载layout /
-(YHPPictrueChoicesFlowLayout )layout {
if(_layout == nil) {
_layout = [[YHPPictrueChoicesFlowLayout alloc]init];
}
return _layout;
}
/ 重写init方法 */

• (instancetype)init
  {
  self = [super initWithCollectionViewLayout:self.layout];
  if (self) {

  }
  return self;
  }
  /** viewDidLoad */

• (void)viewDidLoad {
  [super viewDidLoad];
  self.collectionView.backgroundColor = [UIColor whiteColor];
  /** 注册cell */
  [self.collectionView registerClass:[YHPPictureChoiceCell class] forCellWithReuseIdentifier:YHPPICTURECHOICECELL];
  }

pragma mark - 数据源方法

/** 组数 */

• (NSInteger)numberOfSectionsInCollectionView:(UICollectionView )collectionView {
  return 2;
  }
  /* 每组多少个Item */
• (NSInteger)collectionView:(UICollectionView )collectionView numberOfItemsInSection:(NSInteger)section {
  return 10;
  }
  /* 返回某组某个cell */
• (UICollectionViewCell *)collectionView:(UICollectionView )collectionView cellForItemAtIndexPath:(NSIndexPath )indexPath {
  YHPPictureChoiceCell * cell = [collectionView dequeueReusableCellWithReuseIdentifier:YHPPICTURECHOICECELL forIndexPath:indexPath];
  cell.backgroundColor = [UIColor redColor];
  _cell = cell;
  return _cell;
  }
  / 设置组间距 */
• (UIEdgeInsets)collectionView:(UICollectionView )collectionView layout:(UICollectionViewLayout)collectionViewLayout insetForSectionAtIndex:(NSInteger)section {
  /** 上 左 下 右 */
  return UIEdgeInsetsMake(10, 10, 0, 10);
  }

pragma mark 代理方法

@end

collectionview.gif