moveRowAtIndexPath - 在部分之间移动单元格

在我的 UITableView 中我有这样的关系

Department -< Employees（名称数组）

我已经为每个模型设置了自定义对象。

In my moveRowAtIndexPath，我可以移动到特定的部分；但是，如果我尝试在部分之间移动它，它就会崩溃。

我的想法是我希望能够将“Tom”从“销售”转移到“营销”

#pragma mark - UITableView delegate

-(NSInteger) numberOfSectionsInTableView:(UITableView *)tableView
{
    return [_objects count];
}

-(NSInteger) tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    Department *department = [_objects objectAtIndex:section];
    return [department.employees count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"CellId" forIndexPath:indexPath];

    // Configure the cell...
    Department *department = [_objects objectAtIndex:indexPath.section];
    Employee *employee = [department.employees objectAtIndex:indexPath.row];
    cell.textLabel.text = employee.name;

    return cell;
}

-(NSString *) tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
    Department *department = [_objects objectAtIndex:section];
    return department.name;
}

- (BOOL) tableView: (UITableView *) tableView canEditRowAtIndexPath: (NSIndexPath *) indexPath
{
    return YES;
}

- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath
{
    if (fromIndexPath == toIndexPath ) return;

    Department *department = [_objects objectAtIndex:fromIndexPath.section];
    Employee *employee = [department.employees objectAtIndex:fromIndexPath.row];

    [self.tableView beginUpdates];
    [department.employees removeObjectAtIndex:fromIndexPath.row];
    [department.employees insertObject:employee atIndex:toIndexPath.row];
    [self.tableView endUpdates];

    [tableView reloadData];
}

我如何获得moveRowAtIndexPath允许我将员工从一个部门调到另一个部门（或者更确切地说，从一个部门调到另一个部门）？

非常感谢

// 下面崩溃；

*** Assertion failure in -[UITableView _endCellAnimationsWithContext:], /SourceCache/UIKit_Sim/UIKit-2935.137/UITableView.m:1368
2015-02-20 20:51:15.772 Departments[999:90b] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid update: invalid number of rows in section 0.  The number of rows contained in an existing section after the update (3) must be equal to the number of rows contained in that section before the update (2), plus or minus the number of rows inserted or deleted from that section (0 inserted, 0 deleted) and plus or minus the number of rows moved into or out of that section (0 moved in, 0 moved out).'
*** First throw call stack:
(
    0   CoreFoundation                      0x01a221e4 __exceptionPreprocess + 180
    1   libobjc.A.dylib                     0x017a18e5 objc_exception_throw + 44
    2   CoreFoundation                      0x01a22048 +[NSException raise:format:arguments:] + 136
    3   Foundation                          0x013814de -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:] + 116
    4   UIKit                               0x00539f63 -[UITableView _endCellAnimationsWithContext:] + 13402
    5   UIKit                               0x00549cea -[UITableView endUpdatesWithContext:] + 51
    6   UIKit                               0x00549d18 -[UITableView endUpdates] + 41
    7   Departments                         0x00003a48 -[ViewController tableView:moveRowAtIndexPath:toIndexPath:] + 664
    8   UIKit                               0x005573b4 -[UITableView _endReorderingForCell:wasCancelled:animated:] + 619
    9   UIKit                               0x006e0c4f -[UITableViewCell _grabberReleased:] + 73
    10  UIKit                               0x007d1a1b -[UITableViewCellReorderControl endTrackingWithTouch:withEvent:] + 58
    11  UIKit                               0x005641f1 -[UIControl touchesEnded:withEvent:] + 559
    12  UIKit                               0x004a2ddd -[UIWindow _sendTouchesForEvent:] + 852
    13  UIKit                               0x004a39d1 -[UIWindow sendEvent:] + 1117
    14  UIKit                               0x004755f2 -[UIApplication sendEvent:] + 242
    15  UIKit                               0x0045f353 _UIApplicationHandleEventQueue + 11455
    16  CoreFoundation                      0x019ab77f __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 15
    17  CoreFoundation                      0x019ab10b __CFRunLoopDoSources0 + 235
    18  CoreFoundation                      0x019c81ae __CFRunLoopRun + 910
    19  CoreFoundation                      0x019c79d3 CFRunLoopRunSpecific + 467
    20  CoreFoundation                      0x019c77eb CFRunLoopRunInMode + 123
    21  GraphicsServices                    0x031ee5ee GSEventRunModal + 192
    22  GraphicsServices                    0x031ee42b GSEventRun + 104
    23  UIKit                               0x00461f9b UIApplicationMain + 1225
    24  Departments                         0x000046bd main + 141
    25  libdyld.dylib                       0x02ed5725 start + 0
    26  ???                                 0x00000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb) 

您的问题是您已经操作了数据模型，但没有告诉表视图您所做的更改。

因为你打电话beginUpdates/endUpdates表格视图期待一些变化，所以之后endUpdates它调用numberOfRowsInSection- 返回答案“3” - 但它期望 2+0 （因为你没有告诉它新行）。

您有几个选择：

1 - Use moveRowAtIndexPath:toIndexPath:

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

        Department *department = [_objects objectAtIndex:fromIndexPath.section];
        Employee *employee = [department.employees objectAtIndex:fromIndexPath.row];

        [tableView beginUpdates];
        [department.employees removeObjectAtIndex:fromIndexPath.row];
        [department.employees insertObject:employee atIndex:toIndexPath.row];
        [tableview moveRowAtIndexPath:fromIndexPath toIndexPath:toIndexPath];
        [self.tableView endUpdates];
    }
}

2 - 使用重新加载而不使用beginUpdate/endUpdate

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

        Department *department = [_objects objectAtIndex:fromIndexPath.section];
        Employee *employee = [department.employees objectAtIndex:fromIndexPath.row];

        [department.employees removeObjectAtIndex:fromIndexPath.row];
        [department.employees insertObject:employee atIndex:toIndexPath.row];
        [tableView reloadData];
    }
}