UICollection实现无限滚动

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    // 注册cell
    [self.collectionView registerNib:[UINib nibWithNibName:@"SWTNewsCell" bundle:nil] forCellWithReuseIdentifier:@"news"];
    
    [self.collectionView scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:2500 inSection:0] atScrollPosition:UICollectionViewScrollPositionLeft animated:NO];
}

- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
    return 1;
}

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    return self.newses.count * 1000;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *ID = @"news";
    SWTNewsCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:ID forIndexPath:indexPath];
    
    cell.news = self.newses[indexPath.item % self.newses.count];
    
    return cell;
}