手势识别器滑动以从核心数据中删除

Question

我正在开发一个使用核心数据的应用程序，我想添加一个手势，如果用户向左滑动它将删除数据库中的对象。我已经设置了所有手势识别器部件，但在创建从 tableview 和核心数据中删除对象的方法时遇到了麻烦。因此，如果有人能看到这一点并指出我正确的方向，我将不胜感激！谢谢！

TableView.M

-(void)swipeleft:(UISwipeGestureRecognizer*)gestureRecognizer
{
        NSIndexPath *indexPath = [[self tableView] indexPathForSelectedRow];
        NSManagedObjectContext *context = [self managedObjectContext];

            // Delete object from database
            [context deleteObject:[self.lists objectAtIndex:indexPath.row]];

            // Remove list from table view
            [self.lists removeObjectAtIndex:indexPath.row];
    [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];

        }

@end

错误：

self(ViewController *)  0x8ea0a90   
indexPath=(NSIndexPath *    )  nil  
context+(NSManagedObjectContext *)  0x8d747f0   

Answer 1

试试这个

-(void)swipeleft:(UISwipeGestureRecognizer*)gestureRecognizer
{
    NSIndexPath *indexPath = [[self tableView] indexPathForSelectedRow];
    NSManagedObjectContext *context = [self managedObjectContext];

        // Delete object from database
        [context deleteObject:[self.lists objectAtIndex:indexPath.row]];
        [context save:nil];

        // Remove list from table view
    [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
        [self.lists removeObjectAtIndex:indexPath.row];
}