在删除UITableView单元格之前发出警报 - (UIAlertController)Swift或Objective-C

Question

我想删除一个表视图单元格,但在该操作发生之前,我想给用户一个警报视图.我懂了:

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
    if (editingStyle == UITableViewCellEditingStyleDelete) {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Warning"
                                                        message:@"Are you sure?"
                                                       delegate:self
                                              cancelButtonTitle:@"NO"
                                              otherButtonTitles:@"YES", nil];
        [alert show];

        [self.array removeObjectAtIndex:indexPath.row];//or something similar to this based on your data source array structure
        [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
    }
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    NSString *title = [alertView buttonTitleAtIndex:buttonIndex];
    if([title isEqualToString:@"Nee"])
    {
        NSLog(@"Nothing to do here");
    }
    else if([title isEqualToString:@"Ja"])
    {
        NSLog(@"Delete the cell");

    }
}

但是现在当我在单元格上向右滑动并且删除按钮出现时,我没有AlertView.当我按下删除按钮时,我只获得AlertView.当我按下删除按钮时,将显示该消息但该单元格已被删除.

如何使这项工作？所以当我滑动时有一个AlertView.

Answer 1

关于序列,一切都很好.commitEditingStyle只有在按下删除按钮时才会调用.关键是你实际上在响应警报之前删除了对象.把它改成这个:

在此之前将其添加到.m文件中@implementation:

@interface PutYourViewControllerClassNameHere
@property (strong, nonatomic) NSIndexPath *indexPathToBeDeleted;
@end

然后:

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
    if (editingStyle == UITableViewCellEditingStyleDelete) {

        self.indexPathToBeDeleted = indexPath;

        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Warning"
                                                        message:@"Are you sure?"
                                                       delegate:self
                                              cancelButtonTitle:@"NO"
                                              otherButtonTitles:@"YES", nil];
        [alert show];
        // do not delete it here. So far the alter has not even been shown yet. It will not been shown to the user before this current method is finished.     
    }
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    // This method is invoked in response to the user's action. The altert view is about to disappear (or has been disappeard already - I am not sure) 

    NSString *title = [alertView buttonTitleAtIndex:buttonIndex];
    if([title isEqualToString:@"NO"])
    {
        NSLog(@"Nothing to do here");
    }
    else if([title isEqualToString:@"YES"])
    {
        NSLog(@"Delete the cell");

        [self.array removeObjectAtIndex:[self.indexPathToBeDeleted row]];
        [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:self.indexPathToBeDeleted] withRowAnimation:UITableViewRowAnimationFade];
    }
}

编辑:这应该编译,尽管可能有轻微的语法错误.一般假设:您只处理一个部分.至少只有删除内的一个部分是可能的.

Answer 2

iOS 8 +

iOS 8 推出UIAlertController。这允许您在完成块而不是委托方法中编写删除和取消代码（按照-clickedButtonAtIndex旧的UIAlertView）。

斯威夫特 3

func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
    if editingStyle == .delete {
        let alertController = UIAlertController(title: "Warning", message: "Are you sure?", preferredStyle: .alert)

        let deleteAction = UIAlertAction(title: "Delete", style: .destructive, handler: { (action) in
            self.tableView.deleteRows(at: [indexPath], with: .fade)
        })
        alertController.addAction(deleteAction)

        let cancelAction = UIAlertAction(title: "Cancel", style: .default, handler: nil)
        alertController.addAction(cancelAction)

        present(alertController, animated: true, completion: nil)
    }
}

目标-C

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
    if (editingStyle == UITableViewCellEditingStyleDelete) {
        UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"Warning" message:@"Are you sure?" preferredStyle:UIAlertControllerStyleAlert];

        UIAlertAction *deleteAction = [UIAlertAction actionWithTitle:@"Delete" style:UIAlertActionStyleDestructive handler:^(UIAlertAction * _Nonnull action) {
            [self.tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
        }];
        [alertController addAction:deleteAction];

        UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
            NSLog(@"Don't do anything");
        }];
        [alertController addAction:cancelAction];

        [self presentViewController:alertController animated:YES completion:nil];
    }
}