Question

我尝试添加UILongPressGestureRecognizer以在按住单元格时显示警报视图，但由于某种原因它不能在表视图中的第一个单元格上运行。所以它适用于所有其他单元格，但索引path.row 0的单元格不起作用。有谁知道如何解决这个问题？

我的代码：

UIGestureRecognizerDelegate已添加到.h UILongPressGestureRecognizer * longPress;在顶部实施;

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
    static NSString *identifier = @"activeComputers";
    ActiveComputersCell *cell = [tableView dequeueReusableCellWithIdentifier:identifier];
    if (cell == nil) {
        cell = [[ActiveComputersCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:identifier];
    }

    //gesture recognizer
    longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(detectCellHold)];
    longPress.delegate = self;
    [cell addGestureRecognizer:longPress];

    cell.lblComputer.text = [computer objectAtIndex:indexPath.row];
    cell.lblCustomer.text = [customer objectAtIndex:indexPath.row];
    return cell;
}

- (void)detectCellHold{
    CGPoint p = [longPress locationInView:self.tableView];
    NSIndexPath *indexOfHold = [self.tableView indexPathForRowAtPoint:p];
    if (longPress.state == UIGestureRecognizerStateEnded) {
        NSLog(@"UIGestureRecognizerStateEnded");
        //Do Whatever You want on End of Gesture
    }
    else if (longPress.state == UIGestureRecognizerStateBegan){
        NSLog(@"%ld", (long)indexOfHold.row);
            UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Computer" message:nil delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"Completed", @"Invoice", nil];
            [alert setTag:1];
            [alert show];

    }
}

更新：它在我使用时有效：

- (void)detectCellHold{
                UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Computer" message:nil delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"Completed", @"Invoice", nil];
                [alert setTag:1];
                [alert show];
            }

然而，这会多次显示警报？

Answer 1

添加识别器的好方法是，在滚动过程中，向已经有识别器的单元格添加新识别器，执行以下操作：

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
    static NSString *identifier = @"activeComputers";
    ActiveComputersCell *cell = [tableView dequeueReusableCellWithIdentifier:identifier];
    if (cell == nil) {
        cell = [[ActiveComputersCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:identifier];

        //gesture recognizer
        longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(detectCellHold)];
        longPress.delegate = self;
        [cell addGestureRecognizer:longPress];
    }   

    cell.lblComputer.text = [computer objectAtIndex:indexPath.row];
    cell.lblCustomer.text = [customer objectAtIndex:indexPath.row];
    return cell;
}

Answer 2

跟进@ mityaika07的回答，

为什么在创建单元格时添加手势识别器？

您也可以将其添加到ActiveComputersCell类

   UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(detectCellHold)];
   longPress.delegate = self;
   [self addGestureRecognizer:longPress];

这样，您可以在每次长按时自动获取特定的单元格实例。

UILongPressGestureRecognizer没有在第一个单元格上工作？

2 个答案: