iOS - 如何获取tableview中最后一项的IndexPath？

Question

我想自动滚动到表格视图的末尾.

[tableView scrollToRowAtIndexPath:lastIndexPath atScrollPosition:UITableViewScrollPositionBottom animated:YES];

鉴于我知道tableview中有多少项使用:

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section

如何将IndexPath*转换为此tableView中的最后一项？这是必需的,以便我可以将它作为scrollToRowAtIndexPath的参数提供:atScrollPosition:animated

谢谢!

Answer 1

要获得对最后一节中最后一行的引用...

// First figure out how many sections there are
NSInteger lastSectionIndex = [tableView numberOfSections] - 1;

// Then grab the number of rows in the last section
NSInteger lastRowIndex = [tableView numberOfRowsInSection:lastSectionIndex] - 1;

// Now just construct the index path
NSIndexPath *pathToLastRow = [NSIndexPath indexPathForRow:lastRowIndex inSection:lastSectionIndex];

Answer 2

您可以像这样获取上一部分中最后一行的indexPath.

NSIndexPath *indexPath = [NSIndexPath indexPathForRow:(numberOfRowsInLastSection - 1) inSection:(numberOfSections - 1)];

这里,numberOfSections是您从numberOfSectionsInTableView:方法返回的值.并且,numberOfRowsInLastSection是您从numberOfRowsInSection:表视图中的最后一个部分的方法返回的值.

这可以放在子类或类别中以​​简化:

-(NSIndexPath*)indexPathForLastRow
{
    return [NSIndexPath indexPathForRow:[self numberOfRowsInSection:self.numberOfSections - 1] - 1 inSection:self.numberOfSections - 1];
}

Answer 3

在快速3

let lastRowIndex = tableView.numberOfRows(inSection: tableView.numberOfSections-1)

if (indexPath.row == lastRowIndex - 1) {
     print("last row selected")
}

Answer 4

可能有人会需要同样的UICollectionView,所以我更新了Ryan Grimm的答案:

NSInteger lastSectionIndex = [self.collectionView numberOfSections] - 1;
NSInteger lastItemIndex = [self.collectionView numberOfItemsInSection:lastSectionIndex] - 1;
NSIndexPath *pathToLastItem = [NSIndexPath indexPathForItem:lastItemIndex inSection:lastSectionIndex];

Answer 5

试试这个:

在 cellForRowAtIndexPath

if(indexPath.row == myArray.count -1)

{
     myIndexPath = indexpath;
}

myIndexPath应该是对象 NSIndexPath

Answer 6

这是Swift 4.x中的扩展,考虑到可能没有任何行,因此它避免了超出范围的崩溃.

import UIKit

extension UITableView {
    func lastIndexpath() -> IndexPath {
        let section = max(numberOfSections - 1, 0)
        let row = max(numberOfRows(inSection: section) - 1, 0)

        return IndexPath(row: row, section: section)
    }
}

然后从viewcontroller中调用它:

let lastIndexPath = tableView.lastIndexPath()