UITableView中的moveRowAtIndexPath导致不正确的动画 [英] moveRowAtIndexPath in UITableView causes incorrect animation

问题描述

我有一个简单的UITableView控制器显示CoreData。我试图实现 - （void）tableView：（UITableView *）tableView moveRowAtIndexPath：（NSIndexPath *）fromIndexPath toIndexPath：（NSIndexPath *）toIndexPath;并有动画的麻烦。

如何让动画正确反映核心数据对象发生的变化？

例如：

初始订单：

第2项到顶部：

或，初始订单：

将项目1移动到位置3后：

以下是相关代码：

   - （void）tableView：（UITableView *）tableView moveRowAtIndexPath：（NSIndexPath *）fromIndexPath toIndexPath：（NSIndexPath *）toIndexPath {
 // this实现是从本教程：http://www.cimgf.com/2010/06/05/re-ordering-nsfetchedresultscontroller/ 
 NSMutableArray * things = [[fetchedResultsController fetchedObjects] mutableCopy]; 
 
 //抓取我们正在移动的项目。 
 NSManagedObject * thing = [fetchedResultsController objectAtIndexPath：fromIndexPath]; 
 
 //删除我们从数组中移动的对象。 
 [things removeObject：thing]; 
 //现在重新插入到目的地。 
 [things insertObject：thing atIndex：[toIndexPath row]]; 
 
 //所有对象现在都处于正确的顺序。通过遍历数组更新每个
 //对象的displayOrder字段。 
 
 
 int i = 0; 
 for（NSManagedObject * mo in things）
 {
 [mo setValue：[NSNumber numberWithInt：i ++] forKey：@order]; 
} 
 
 
 NSLog（@things：％@，things）; 
 [things release]，things = nil; 
 
 [managedObjectContext save：nil]; 
} 
  

和委托：

（NSFetchedResultsChangeType）类型newIndexPath：（NSIndexPath *）newIndexPath {NSFetchedResultsController *）控制器didChangeObject：（id）anObject atIndexPath：（NSIndexPath *）indexPath forChangeType：
NSLog（@didChangeObject：）;
UITableView * tableView = self.tableView;

switch（type）{
case NSFetchedResultsChangeInsert：
NSLog（@ResultsChangeInsert：）;
[tableView insertRowsAtIndexPaths：[NSArray arrayWithObject：newIndexPath] withRowAnimation：UITableViewRowAnimationFade];
break;

case NSFetchedResultsChangeDelete：
[tableView deleteRowsAtIndexPaths：[NSArray arrayWithObject：indexPath] withRowAnimation：UITableViewRowAnimationFade];
break;

case NSFetchedResultsChangeMove：
[tableView deleteRowsAtIndexPaths：[NSArray arrayWithObject：indexPath] withRowAnimation：UITableViewRowAnimationFade];
[tableView insertRowsAtIndexPaths：[NSArray arrayWithObject：newIndexPath] withRowAnimation：UITableViewRowAnimationFade];
break;
}
}

解决方案

问题是由代理干扰我的重排序实现造成的。
在保存ManagedObjectContext之前添加了一个bool：

reordering = YES;
[managedObjectContext save：nil];

并使用它跳过任何FetchedResultsController委托函数。不是最好的解决方案，但它适用于这个实现。我会感谢任何评论/答案解释为什么这种情况发生。

  / ** 
委派NSFetchedResultsController的方法来响应添加，删除等。 
 * / 
 
  - （void）controllerWillChangeContent：（NSFetchedResultsController *）controller {
 
 if（！reordering）{
 
提取控制器即将开始发送更改通知，因此请准备表视图以进行更新。 
 NSLog（@controllerWillChangeContent：）; 
 
 [self.tableView beginUpdates]; 
 
} 
 
} 
 
 
  - （void）controller：（NSFetchedResultsController *）controller didChangeObject：（id）anObject atIndexPath： NSIndexPath *）indexPath forChangeType：（NSFetchedResultsChangeType）type newIndexPath：（NSIndexPath *）newIndexPath {
 if（！reordering）{
 
 NSLog（@didChangeObject：）; 
 UITableView * tableView = self.tableView; 
 
 switch（type）{
 case NSFetchedResultsChangeInsert：
 NSLog（@ResultsChangeInsert：）; 
 [tableView insertRowsAtIndexPaths：[NSArray arrayWithObject：newIndexPath] withRowAnimation：UITableViewRowAnimationFade]; 
 break; 
 
 case NSFetchedResultsChangeDelete：
 [tableView deleteRowsAtIndexPaths：[NSArray arrayWithObject：indexPath] withRowAnimation：UITableViewRowAnimationFade]; 
 break; 
 
 / * case NSFetchedResultsChangeMove：
 [tableView deleteRowsAtIndexPaths：[NSArray arrayWithObject：indexPath] withRowAnimation：UITableViewRowAnimationFade]; 
 [tableView insertRowsAtIndexPaths：[NSArray arrayWithObject：newIndexPath] withRowAnimation：UITableViewRowAnimationFade]; 
 break; * / 
} 
 
} 
} 
 
  - （void）controller：（NSFetchedResultsController *）controller didChangeSection： < NSFetchedResultsSectionInfo>）sectionInfo atIndex：（NSUInteger）sectionIndex forChangeType：（NSFetchedResultsChangeType）type {
 if（！reordering）{
 
 NSLog（@didChangeSelection： 
 switch（type）{
 case NSFetchedResultsChangeInsert：
 [self.tableView insertSections：[NSIndexSet indexSetWithIndex：sectionIndex] withRowAnimation：UITableViewRowAnimationFade]; 
 break; 
 
 case NSFetchedResultsChangeDelete：
 [self.tableView deleteSections：[NSIndexSet indexSetWithIndex：sectionIndex] withRowAnimation：UITableViewRowAnimationFade]; 
 break; 
} 
} 
} 
 
 
  - （void）controllerDidChangeContent：（NSFetchedResultsController *）controller {
 if（！reordering）{
 
 NSLog（@didChangeContent：）; 
 //获取控制器已发送所有当前更改通知，因此请告知表视图来处理所有更新。 
 [self.tableView endUpdates]; 
} else {
 reordering = NO; 
} 
 
} 
  

I have a simple UITableView Controller that shows CoreData. I'm trying to implement - (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath; and having trouble with the animation. The Core Data store gets updated, but the animation is not working.

How can I get the animation to correctly reflect the changes that are happening to the core data objects?

For example:

Initial order:

After item 2 to the top:

or, Initial Order:

After moving item 1 to position 3:

Here's the relevant code:

- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath {
//this implementation is from this tutorial: http://www.cimgf.com/2010/06/05/re-ordering-nsfetchedresultscontroller/
NSMutableArray *things = [[fetchedResultsController fetchedObjects] mutableCopy];

// Grab the item we're moving.
NSManagedObject *thing = [fetchedResultsController objectAtIndexPath:fromIndexPath];

// Remove the object we're moving from the array.
[things removeObject:thing];
// Now re-insert it at the destination.
[things insertObject:thing atIndex:[toIndexPath row]];

// All of the objects are now in their correct order. Update each
// object's displayOrder field by iterating through the array.


int i = 0;
for (NSManagedObject *mo in things)
{
    [mo setValue:[NSNumber numberWithInt:i++] forKey:@"order"];
}


NSLog(@"things: %@", things);
[things release], things = nil; 

[managedObjectContext save:nil];            
}

and the delegate:

- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath {
NSLog(@"didChangeObject:");
UITableView *tableView = self.tableView;

switch(type) {
    case NSFetchedResultsChangeInsert:
        NSLog(@"ResultsChangeInsert:");
        [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
        break;

    case NSFetchedResultsChangeDelete:
        [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
        break;

    case NSFetchedResultsChangeMove:
        [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
        [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
        break;
}
}

解决方案

The problem was caused by the delegate interfering with my reordering implementation. I added a bool before saving my ManagedObjectContext:

reordering = YES; [managedObjectContext save:nil];

and used it to skip out of any of the FetchedResultsController Delegate functions. Not the best solution, but it works for this implementation. I'd be grateful for any comments / answers explaining why this happened.

/**
Delegate methods of NSFetchedResultsController to respond to additions, removals and so  on.
*/

- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller {

if (!reordering) {

// The fetch controller is about to start sending change notifications, so prepare the table view for updates.
NSLog(@"controllerWillChangeContent:");

[self.tableView beginUpdates];

}

}


- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath {
if (!reordering) {

    NSLog(@"didChangeObject:");
    UITableView *tableView = self.tableView;

    switch(type) {
        case NSFetchedResultsChangeInsert:
            NSLog(@"ResultsChangeInsert:");
            [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
            break;

        case NSFetchedResultsChangeDelete:
            [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
            break;

        /*case NSFetchedResultsChangeMove:
            [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
            [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
            break;*/
    }

}
}

- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type {
if (!reordering) {

    NSLog(@"didChangeSelection:");
    switch(type) {
        case NSFetchedResultsChangeInsert:
            [self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
            break;

        case NSFetchedResultsChangeDelete:
            [self.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
            break;
    }
}
}


- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
if (!reordering) {

    NSLog(@"didChangeContent:");
    // The fetch controller has sent all current change notifications, so tell the table view to process all updates.
    [self.tableView endUpdates];
}else {
    reordering = NO;
}

}

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