Question

我有一个UITableView，每行包含一个使用UITableViewCellAccessoryCheckmark的复选框。我无法弄清楚如何使用didSelectRowAtIndexPath方法取消选中所有复选框。

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {  

    UITableViewCell *oldCell;

    int count = [self.myTableRowNamesArray count];

    for (NSUInteger i = 0; i < count; ++i) {                                
        // Uncheck all checkboxes
        // OF COURSE THIS DOESN'T WORK
        // BECAUSE i IS AN INTEGER AND INDEXPATH IS A POINTER
        FOO: oldCell = [myTableView cellForRowAtIndexPath:(int)i];
        // GOOD CODE:
        oldCell = [penanceOptionsTableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:i inSection:0]];
        oldCell.accessoryType = UITableViewCellAccessoryNone;
    }
    UITableViewCell *newCell = [myTableView cellForRowAtIndexPath:indexPath];
    newCell.accessoryType = UITableViewCellAccessoryCheckmark;
}

Answer 1

我建议将选定的索引存储在某些ivar中，而不是修改.accessoryType中所有单元格的didSelectRowAtIndexPath:，并更改数据中的.accessoryType来源的-tableView:cellForRowAtIndexPath:方法，即

-(void)tableView:(UITableView*)tableView didSelectRowAtIndexPath:(NSIndexPath*)indexPath { 
   self.selectedIndexPath = indexPath;
   [tableView reloadData];
}

-(UITableViewCell*)tableView:(UITableView*)tableView cellForRowAtIndexPath:(NSIndexPath*)indexPath {
   ...
   cell.accessoryType = [indexPath compare:self.selectedIndexPath] == NSOrderedSame
                          ? UITableViewCellAccessoryCheckmark
                          : UITableViewCellAccessoryNone;
   ...
}

这样，只会影响可见细胞，并且不需要修改屏幕外的其他数百万个细胞。

非常正确，在选择单元格的一般情况下，这是Swift中的完整实现..您可以根据需要在类中的其他位置使用selectedIndexPath。例如，在cellForRowAtIndexPath中选择适当的单元格原型。

//  SelectingTableViewController

import UIKit

class SelectingTableViewController: UITableViewController   
    {
    internal var selectedIndexPath:NSIndexPath? = nil

    override func viewDidLoad()
        {
        super.viewDidLoad()
        tableView.estimatedRowHeight = 68.0
        tableView.rowHeight = UITableViewAutomaticDimension

        self.clearsSelectionOnViewWillAppear = false;
        }

    override func tableView
        (tableView:UITableView, didSelectRowAtIndexPath indexPath:NSIndexPath)
            {
            print("did select....")

            // in fact, was this very row selected,
            // and the user is clicking to deselect it...
            // if you don't want "click a selected row to deselect"
            // then on't include this clause.
            if selectedIndexPath == indexPath
                {
                print("(user clicked on selected to deselect)")
                selectedIndexPath = nil
                tableView.reloadRowsAtIndexPaths(
                    [indexPath],
                    withRowAnimation:UITableViewRowAnimation.None)

                tableView.deselectRowAtIndexPath(indexPath, animated:false)
                return
                }

            // in fact, was some other row selected??
            // user is changing to this row? if so, also deselect that row
            if selectedIndexPath != nil
                {
                let pleaseRedrawMe = selectedIndexPath!
                // (note that it will be drawn un-selected
                // since we're chaging the 'selectedIndexPath' global)
                selectedIndexPath = indexPath
                tableView.reloadRowsAtIndexPaths(
                    [pleaseRedrawMe, indexPath],
                    withRowAnimation:UITableViewRowAnimation.None)
                return;
                }

            // no previous selection.
            // simply select that new one the user just touched.
            // note that you can not use Apple's willDeselectRowAtIndexPath
            // functions ... because they are freaky
            selectedIndexPath = indexPath
            tableView.reloadRowsAtIndexPaths(
                [indexPath],
                withRowAnimation:UITableViewRowAnimation.None)

            }

    }

Answer 2

for (UITableViewCell *cell in [myTableView visibleCells]) {
    cell.accessoryType = UITableViewCellAccessoryNone;
}

但实际上，你最好只修改一个实际上有复选标记设置的单元格。无论如何，您必须将此信息存储在模型中的某个位置。

Answer 3

您可能正在使用此方法设置某种属性。所以我做的是：

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    // 1. first unsetting the property
    [object someProperty:nil];

    // 2. call the reloadData method to uncheck all the checkmarks
    [tableView reloadData];

    // 3. check the selected cell
    UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
    [cell setAccessoryType:UITableViewCellAccessoryCheckmark];

    // 4. set the checked property
    [object setSomeProperty:[indexpath row]];
}

在我的cellForRowAtIndexPath方法中，我得到了类似下面的代码：

    if([object someProperty] == [indexpath row]){
        [cell setAccessoryType:UITableViewCellAccessoryCheckmark];        
    } else {
        [cell setAccessoryType:UITableViewCellAccessoryNone];
    }

Answer 4

是的，cellForRowAtIndexPath:使用NSIndexPath而不是整数，因此请使用

创建indexpath

indexPathForRow:inSection:

如果你正在使用一个部分，那么你的循环很好，只需要传入i in row，0传递给section。

如何使用UITableViewCellAccessoryCheckmark取消选中所有行

4 个答案: