ios - 移动行在索引路径 : how to delete section once last row is moved to another section

Question

我有一个包含多个部分的表格 View 。我希望能够将行从一个部分移动到另一个部分，并在没有行时删除一个部分。我正在尝试通过 moveRowAtIndexPath 执行此操作，但我的代码不起作用并抛出 NSRangeException 异常。

这是一个代码示例:

- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath {

    NSUInteger fromSection = [fromIndexPath section];
    NSUInteger fromRow = [fromIndexPath row];
    NSString *fromKey = [self.keys objectAtIndex:fromSection];
    NSMutableArray *fromEventSection = [self.eventsDict objectForKey:fromKey];

    NSUInteger toSection = [toIndexPath section];
    NSUInteger toRow = [toIndexPath row];
    NSString *toKey = [self.keys objectAtIndex:toSection];
    NSMutableArray *toEventSection = [self.eventsDict objectForKey:toKey];

    id object = [[fromEventSection objectAtIndex:fromRow] retain];
    [fromEventSection removeObjectAtIndex:fromRow];
    [toEventSection insertObject:object atIndex:toRow];
    [object release];
    // The above code works just fine!

    // Try to delete an empty section. Here is where trouble begins:
    if ((fromSection != toSection) && [fromEventSection count] == 0) {
        [self.keys removeObjectAtIndex:fromSection];
        [self.eventsDict removeObjectForKey:fromKey];

        [tableView deleteSections:[NSIndexSet indexSetWithIndex:fromSection] withRowAnimation:UITableViewRowAnimationFade];
    }

Answer 1

我有幸在 moveRowAtIndexPath 方法结束后的一个 block 中执行 deleteSections 方法，方法是将删除包装在 dispatch_async 中。

    dispatch_async(dispatch_get_main_queue(), ^{
        if ((fromSection != toSection) && [fromEventSection count] == 0) {
            [self.keys removeObjectAtIndex:fromSection];
            [self.eventsDict removeObjectForKey:fromKey];
            [tableView deleteSections:[NSIndexSet indexSetWithIndex:fromSection] withRowAnimation:UITableViewRowAnimationFade];
        }
    });