Unlimited image carousel-the simplest way to achieve unlimited image carousel

Unlimited image carousel-the simplest way to achieve unlimited image carousel

In collectionView, only three cells are displayed as the second cell.

-(UICollectionViewCell *) collectionView :( UICollectionView *) collectionView cellForItemAtIndexPath :( NSIndexPath *) indexPath {

CycleViewCell * cell = [collectionViewdequeueReusableCellWithReuseIdentifier: @ "Cell" forIndexPath: indexPath];

// IndexPath. item-1 is equivalent to adding 1 to the left of index and one to the right

// IndexPath. item-1. If you move left, the third cell 2-1 will be displayed, which is equivalent to self. currentIndex + 1.

// IndexPath. item-1. If you move the value to the right, the first cell 0-1 will be displayed, which is equivalent to self. currentIndex-1.

NSInteger index = (self. currentIndex + indexPath. item-1 + self. imageURLs. count) % self. imageURLs. count;

Cell. imageURL = self. imageURLs [index];

Return cell;

}

// Method called after the rolling view stops rolling completely

-(Void) scrollViewDidEndDecelerating :( UIScrollView *) scrollView {

// 1. Based on the contentOffset, you can determine the page to stay on.

Int page = scrollView. contentOffset. x/scrollView. bounds. size. width;

NSLog (@ "page % d", page );

// 2. If it is page 0th, self. currentIndex-1, if it is page 2nd, self. currentIndex + 1;

Self. currentIndex = (self. currentIndex + page-1 + self. imageURLs. count) % self. imageURLs. count;

// 3. Let the collection scroll to display the first page

NSIndexPath * indexPath = [NSIndexPathindexPathForItem: 1 inSection: 0];

[Self. collectionViewscrollToItemAtIndexPath: indexPathatScrollPosition: UICollectionViewScrollPositionCenteredHorizontallyanimated: NO];

}

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