ios基于UICollectionView实现横向瀑布流

3、上边的这个布局类可以直接复制粘贴下来。然后就是创建你的UICollectionView 

在collectionView的cell中可以直接创建imageView或者是label添加到cell上，用来显示数据。 
collectionView默认section缩进左右是0 
调节横向cell间距 
layout.minimumLineSpacing = 10; 
调节纵向cell间距 
layout.minimumInteritemSpacing = 20; 
调节瀑布流显示的行数，当然了你的collectionView的高（宽）足够显示几行（列）就会自动显示多上行（列）； 
layout.numberOfColumns = 3;

#import "RootViewController.h"
#import "WaterfallFlowLayout.h"

@interface RootViewController () <UICollectionViewDataSource,UICollectionViewDelegateFlowLayout,WaterfallFlowLayoutDelegate>
{
  UICollectionView * _collectionView;
}
@end

@implementation RootViewController
- (void)dealloc {
  [_collectionView release];
  [super dealloc];

}

- (void)viewDidLoad {
  [super viewDidLoad];
  // 创建集合视图
  [self createCollectionView];
}

- (UICollectionViewLayout *)createLayout {
#if 1
  WaterfallFlowLayout * layout = [[WaterfallFlowLayout alloc] init];
  layout.sectionInset = UIEdgeInsetsMake(20, 20, 20, 20);
  layout.minimumLineSpacing = 10;
  layout.minimumInteritemSpacing = 20;
  layout.numberOfColumns = 3;
  layout.delegate = self;
  [self performSelector:@selector(changeLayout:) withObject:layout afterDelay:3];

#else
  UICollectionViewFlowLayout * layout = [[UICollectionViewFlowLayout alloc] init];

  layout.minimumLineSpacing = 10;
  layout.itemSize = CGSizeMake(150, 100);
  layout.sectionInset = UIEdgeInsetsMake(10, 10, 10, 10);

#endif


  return [layout autorelease];
}
- (void)changeLayout:(WaterfallFlowLayout *)layout {
  layout.numberOfColumns = 3;
}


- (void)createCollectionView {
  CGRect frame = CGRectMake(0, 20, VIEW_WIDTH, VIEW_HEIGHT-20);
  _collectionView = [[UICollectionView alloc] initWithFrame:frame collectionViewLayout:[self createLayout]];

  _collectionView.backgroundColor = [UIColor cyanColor];
  // 设置代理
  _collectionView.delegate = self;
  _collectionView.dataSource = self;

  // 注册cell 类型 及 复用标识
  [_collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"cellId"];


  [self.view addSubview:_collectionView];
}

#pragma mark - UICollectionViewDataSource

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
  return 102;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
  UICollectionViewCell * cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"cellId" forIndexPath:indexPath];

  UILabel * label = nil;
  NSArray * array = cell.contentView.subviews;
  if (array.count) {
    label = array[0];
  }else {
    label = [[UILabel alloc] init];
//    label.frame = cell.bounds;
    label.textAlignment = NSTextAlignmentCenter;
    label.font = [UIFont systemFontOfSize:50];
    [cell.contentView addSubview:label];
    [label release];
  }
  label.frame = cell.bounds;
  label.text = [NSString stringWithFormat:@"%ld",indexPath.item];
  label.textColor = [UIColor whiteColor];
  cell.backgroundColor = RandomColor;

  return cell;
}

- (CGSize) collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
  return CGSizeMake( arc4random()%100+200, 110);
}

-(CGFloat) WaterfallFlowLayout:(WaterfallFlowLayout *)layout widthForItemAtIndexPath:(NSIndexPath *)indexPath{
  return arc4random()%150+50;
}

-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{
  NSLog(@"点击了第 %ld 组，第 %ld 行",indexPath.section,indexPath.row);
}

- (void)didReceiveMemoryWarning {
  [super didReceiveMemoryWarning];
}


@end								 
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