• iOSCollectioView滚动到指定section的方法


    CollectioView滚动到指定section的方法

     

    项目中的需求:collectionView顶部有一个scrollView组成的标签,点击标签,让collectionView滚动到指定的行,滚动collectionView自动切换到顶部指定的标签

    实现方法如下:

    1. 保证collectionView全部加载完毕,我这里通过一个bool的标志位来标示
      -(void)collectionView:(UICollectionView *)collectionView willDisplayCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath
      {
            if([indexPath row] == ((NSIndexPath*)[[collectionView indexPathsForVisibleItems] lastObject]).row){
                self.isLoaded = YES;
            }
       }
    2. 标签点击了CollectionView滚动到指定行
            if (self.isLoaded) {
                
                // scroll to selected index
                NSIndexPath* cellIndexPath = [NSIndexPath indexPathForItem:0 inSection:index+1];
                UICollectionViewLayoutAttributes* attr = [self.collectionView.collectionViewLayout layoutAttributesForSupplementaryViewOfKind:UICollectionElementKindSectionHeader atIndexPath:cellIndexPath];
                UIEdgeInsets insets = self.collectionView.scrollIndicatorInsets;
                
                CGRect rect = attr.frame;
                rect.size = self.collectionView.frame.size;
                rect.size.height -= insets.top + insets.bottom;
                CGFloat offset = (rect.origin.y + rect.size.height) - self.collectionView.contentSize.height;
                if ( offset > 0.0 ) rect = CGRectOffset(rect, 0, -offset);
                
                [weakSelf.collectionView scrollRectToVisible:rect animated:YES];
            }
    
    3. CollectionView滚动到指定行的时候,同时切换标签滚动
        -(void)scrollViewDidScroll:(UIScrollView *)scrollView{
            static NSInteger currentIndex = 0;
    
            NSInteger index=scrollView.contentOffset.y;
            CGRect visibleRect = (CGRect){.origin = self.collectionView.contentOffset, .size = self.collectionView.bounds.size};
            CGPoint visiblePoint = CGPointMake(CGRectGetMidX(visibleRect), CGRectGetMidY(visibleRect));
            NSIndexPath *visibleIndexPath = [self.collectionView indexPathForItemAtPoint:visiblePoint];
    //        NSLog(@"%@",visibleIndexPath);
            if (currentIndex == visibleIndexPath.section || visibleIndexPath == nil) {
                return;
            }
            currentIndex = visibleIndexPath.section;
    
           [self.itemTool itemScrollToPositionWithIndex:currentIndex isJump:YES];
        }
  • 相关阅读:
    kubernetes之secret
    kubernetes的核心组件功能
    ingress
    服务发现: coredns
    service
    deployment控制pod进行滚动更新以及回滚
    init container
    service与pod关联
    Joiner
    SpringMVC 用注解Annotation驱动的IoC功能@Autowired @Component
  • 原文地址:https://www.cnblogs.com/sunfuyou/p/7460825.html
Copyright © 2020-2023  润新知