01.轮播图之三 ： collectionView 轮播

个人觉得 collection view 做轮播是最方便的，设置下flowlayout 其他不会有很大的变动，没有什么逻辑的代码

let's begin……

创建自定义的view

.h 声明文件

@interface CollectionViewShuffling : UIView@property (nonatomic,strong)NSArray *array;@end

.m 实现文件

@interface CollectionViewShuffling ()<UICollectionViewDelegate, UICollectionViewDataSource>@property (nonatomic,strong)UICollectionView *collectionView;
@property (nonatomic,strong)NSMutableArray *collectionArray;@end@implementation CollectionViewShuffling
@synthesize array = _array;-(instancetype)initWithFrame:(CGRect)frame{if (self == [super initWithFrame:frame]) {}return self;
}
/**
这个是横向滚动轮播的重点研究对象
*/
-( UICollectionViewFlowLayout *)creatFlowLayout{// 创建UICollectionViewFlowLayout约束对象UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc] init];// 设置item的Size大小flowLayout.itemSize = CGSizeMake(self.frame.size.width, self.frame.size.height);// 设置uicollection 的 横向滑动flowLayout.scrollDirection = UICollectionViewScrollDirectionHorizontal;flowLayout.minimumLineSpacing = 0;return  flowLayout;
}- (UICollectionView *)collectionView
{if (!_collectionView) {UICollectionViewFlowLayout *flowLayout = [self creatFlowLayout];_collectionView = [[UICollectionView alloc] initWithFrame:CGRectMake(0, 0, self.frame.size.width,  self.frame.size.height) collectionViewLayout:flowLayout];[self addSubview:_collectionView];// 设置代理_collectionView.delegate = self;_collectionView.dataSource = self;
//        _collectionView.showsHorizontalScrollIndicator = NO;// 设置不展示滑动条_collectionView.pagingEnabled = YES; // 设置整页滑动// 设置当前collectionView 到哪个位置(indexPath row 0 section 取中间(50个))
        [_collectionView registerNib:[UINib nibWithNibName:@"ShufflingItem" bundle:nil] forCellWithReuseIdentifier:@"ShufflingItem"];}return _collectionView;
}-(void)setArray:(NSArray *)array{NSAssert(array.count != 0, @"传入的滚动数组是 空的");_array = array;[self prepareData];[self prepareUI];
}-(void)prepareUI{[self.collectionView scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:1 inSection:0] atScrollPosition:UICollectionViewScrollPositionLeft animated:false];[self.collectionView reloadData];
}- (void)prepareData{self.collectionArray = [NSMutableArray new];//    首位 添加数组最后的元素
    [self.collectionArray addObject:_array.lastObject];//   添加数组元素
    [self.collectionArray addObjectsFromArray:_array];//    末尾 补充第一个元素
    [self.collectionArray addObject:_array.firstObject];
}
/*collection view  delegate*/
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{return 1;
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{return self.collectionArray.count;
}- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{ShufflingItem *item = [collectionView dequeueReusableCellWithReuseIdentifier:@"ShufflingItem" forIndexPath:indexPath];if (!item) {item = [[ShufflingItem alloc] init];}item.imageView.backgroundColor = self.collectionArray[indexPath.row];return item;
}-(void)scrollViewDidScroll:(UIScrollView *)scrollView{if (scrollView == self.collectionView) {NSLog(@"scroll content %@",NSStringFromCGPoint(scrollView.contentOffset));//检测移动的位移if (scrollView.contentOffset.x == (self.collectionArray.count-1)*(self.frame.size.width) ) {[self.collectionView scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:1 inSection:0] atScrollPosition:UICollectionViewScrollPositionLeft animated:false];}else if (scrollView.contentOffset.x == 0){[self.collectionView scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:(self.collectionArray.count-2) inSection:0] atScrollPosition:UICollectionViewScrollPositionLeft animated:false];}else{//            正常滚动
        }}
}

 最简单的collection 轮播，实现啦……

总结下，他的实现为什么如此简单

1. collection view 有个flow layout 设置这个属性就可以让他横向滚动，竖向滚动
2. 还有一个重点 声明下 collection view 使用 item cell 的时候，是必须注册的

调用方法：：：：

-(void)prepareCollectShuffling{CollectionViewShuffling *collectShuffling = [[CollectionViewShuffling alloc]initWithFrame:CGRectMake(10, 320, self.view.frame.size.width -20, 220)];[self.view addSubview:collectShuffling];;collectShuffling.array = self.arr;
}

 

这个写完，距离成功又进了一步，继续………………