自定义UICollectionView横向滑动分页功能

1. pagingEnabled = true 可根据页面宽度进行分页

2. 自定义分页功能

pagingEnabled一定要设为false

在scrollViewWillEndDragging:withVelocity:targetContentOffset:里自定义滑动方法
targetContentOffset 是个指针，可以修改这个参数的值，让scrollView最终停止在目标位置。

- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset
{
 
 float pageWidth = self.collectionView.width - 28*2 + 10; // width + space
 
 float currentOffset = scrollView.contentOffset.x;
 float targetOffset = targetContentOffset->x;
 float newTargetOffset = 0;
 
 if (targetOffset > currentOffset)
     newTargetOffset = ceilf(currentOffset / pageWidth) * pageWidth;
 else
     newTargetOffset = floorf(currentOffset / pageWidth) * pageWidth;
 
 if (newTargetOffset < 0)
     newTargetOffset = 0;
 else if (newTargetOffset > scrollView.contentSize.width)
     newTargetOffset = scrollView.contentSize.width;
 
 targetContentOffset->x = currentOffset;
 
 [scrollView setContentOffset:CGPointMake(newTargetOffset, 0) animated:YES];
 
 NSLog(F(@"%@",@(newTargetOffset)));

}

若为collectionView也可在UICollectionViewFlowLayout子类里重写

• (CGPoint)targetContentOffsetForProposedContentOffset:(CGPoint)proposedContentOffset withScrollingVelocity:(CGPoint)velocity;