根据UIScrollView 滑动获取当前页数

#pragma mark --
#pragma mark --  UIScrollViewDelegate
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{
    
    CGFloat pageWidth = mainScrollView.frame.size.width;
    
    int currentPage = floor((mainScrollView.contentOffset.x - pageWidth / 2) / pageWidth) + 1;

if (currentPage == _fullImagesArray.count - 1) {
        NSLog(@"---最后一页---");
    }else if (currentPage == 0){
        NSLog(@"---第一页---");
    }else{
        NSLog(@"---中间页---");
    }
    
}