在看到这个标题的时候，相信大家心里肯定会想，无限循环轮播的博客已经满天飞了，好有必要写么。这里我想声明一下，这里的无线滑动，但是数据却不循环。
实现原理
由于业务的需求，需要有大量的数据呈现在collectionView上，但是又不想刷新全部的数据，因此需要制定collectionView的cell的数量为有限的。针对这一种情况，我们需要保证页面刷新数据源的索引和页面滑动的索引是不致的。同时滑动停止后，悄悄的将collectionView恢复到初始的位置。
具体源码如下：
@interface JKReadViewController ()<UIScrollViewDelegate>
{
NSArray *_datas;
}
@property (nonatomic,assign) NSInteger currentIndex;
@property (nonatomic,assign) NSInteger cellCount;
@property (nonatomic,assign) NSInteger sectionNum;
@end
@implementation JKReadViewController
- (UICollectionViewFlowLayout *)collectionViewLayout{
UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc] init];
flowLayout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
return flowLayout;
}
- (Class)cellClass{
return [JKPageCollectionCell class];
}
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
}
- (void)configOrigin{
self.sectionNum = floor(self.dataIndex/self.cellCount);
self.currentIndex = 1;//当前CollectionView的索引
NSIndexPath *idxPath = [NSIndexPath indexPathForItem:1 inSection:0];
[self.collectionView scrollToItemAtIndexPath:idxPath atScrollPosition:0 animated:NO];
}
- (void)viewDidAppear:(BOOL)animated{
[super viewDidAppear:animated];
[self configOrigin];
}
- (void)configUI{
[super configUI];
self.collectionView.pagingEnabled = YES;
self.collectionView.showsHorizontalScrollIndicator = NO;
self.collectionView.bounces = NO;
}
-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{
NSInteger index = scrollView.contentOffset.x/ scrollView.bounds.size.width;
if (index>self.currentIndex) {
self.dataIndex++;//数据源的索引
}else if (index< self.currentIndex){
self.dataIndex--;
self.dataIndex = self.dataIndex<0?0:self.dataIndex;
}
NSIndexPath *indexPath = [NSIndexPath indexPathForItem:1 inSection:0];
[self.collectionView reloadItemsAtIndexPaths:@[indexPath]];
dispatch_async(dispatch_get_main_queue(), ^{
[self.collectionView scrollToItemAtIndexPath:indexPath atScrollPosition:0 animated:NO];
});
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath*)indexPath {
JKPageCollectionCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:[JKPageCollectionCell CellIndentifier] forIndexPath:indexPath];
NSString *title = self.datas[self.dataIndex];
[cell updateViewWithModel:title];
return cell;
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{
return self.cellCount;
}
- (NSArray *)datas{//模拟的大量的数据源
if (!_datas) {
NSMutableArray *tempArray = [NSMutableArray new];
for (NSInteger i = 0; i< 1000; i++) {
NSString *string = [NSString stringWithFormat:@"%@",@(i)];
[tempArray addObject:string];
}
_datas = [tempArray copy];
}
return _datas;
}
- (NSInteger)cellCount{
return 3;//单元格的数量
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
@end实现动画效果如下：
实现还不完美，欢迎大家多多提建议哦
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