UITableViewCell 展开和折叠 [英] UITableViewCell expand and collapse

问题描述

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
 //case 1
 //The user is selecting the cell which is currently expanded
 //we want to minimize it back
 if(selectedIndex == indexPath.row)
 {
    selectedIndex = -1;
    [tableView reloadRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];

    return;
}

//case 2 
//First we check if a cell is already expanded.
//If it is we want to minimize make sure it is reloaded to minimize it back
if(selectedIndex >= 0)
{
    NSIndexPath *previousPath = [NSIndexPath indexPathForRow:selectedIndex inSection:0];
    selectedIndex = indexPath.row;
    [tableView reloadRowsAtIndexPaths:[NSArray arrayWithObject:previousPath] withRowAnimation:UITableViewRowAnimationFade];        
}


//case 3
//Finally set the selected index to the new selection and reload it to expand
selectedIndex = indexPath.row;
[tableView reloadRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];

}

注意案例 1 和案例 2 如何关联折叠已经展开的行，而案例 3 是关于展开未展开的行.

Notice how case 1 and case 2 are related collpasing already expanded row where as case 3 is about expanding the unexpanded row.

展开和折叠都使用与 reloadRowsAtIndexPaths 函数相同的函数.

Both the expand and collapse use the same function of reloadRowsAtIndexPaths function.

对我来说，问题是一个切换按钮，当它展开时，再次运行该功能会折叠，而当它折叠时，它会展开??

推荐答案

当你调用 reloadRowsAtIndexPaths: 表视图将通过调用你的 tableView 实现重新加载那些行:cellForRowAtIndexPath: 在你的 UITableViewDataSource 中.您可以在那里返回一个单元格，该单元格使用 selectedIndex 变量来决定它应该显示为展开还是折叠(无论这对您的特定应用程序意味着什么).它还会在您的 UITableViewDelegate 上调用 tableView:heightForRowAtIndexPath:(是的，这在委托中很愚蠢)所以如果您的单元格高度改变了这个方法也应该返回一个值取决于 selectedIndex.

What will happen is that when you call reloadRowsAtIndexPaths: the table view will reload those rows by calling your implementation of tableView:cellForRowAtIndexPath: in your UITableViewDataSource. It is up to you to return a cell there which uses the selectedIndex variable to decide if it should appear expanded or collapsed (whatever that means for your specific application). It will also call tableView:heightForRowAtIndexPath: on your UITableViewDelegate (yes, it is silly that this is in the delegate) so if your cell height changes this method too should return a value depending on selectedIndex.

另外，我建议你只调用一次 reloadRowsAtIndexPaths:，就像这样:

Also, I would suggest you only call reloadRowsAtIndexPaths: once, like this:

NSMutableArray* rows = [NSMutableArray arrayWithCapacity:2];
// Case 2
if(selectedIndex >= 0)
{
    NSIndexPath* previousPath = [NSIndexPath indexPathForRow:selectedIndex inSection:0];
    [rows addObject:previousPath];
}
// Case 3
selectedIndex = indexPath.row;
[rows addObject:indexPath];
[tableView reloadRowsAtIndexPaths:rows withRowAnimation:UITableViewRowAnimationFade];

这篇关于UITableViewCell 展开和折叠的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！