插入/删除顶部/底部单元格时更新旧/新顶部/底部单元格的背景视图 [英] Update old/new top/bottom cells' backgroundView when inserting/deleting top/bottom cells

问题描述

这是NSFetchedResultsControllerDelegate文档中给出的模板代码:

This is the template code given in the doc of NSFetchedResultsControllerDelegate:

- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller {
    [self.tableView beginUpdates];
}


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

    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)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject
    atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type
    newIndexPath:(NSIndexPath *)newIndexPath {

    UITableView *tableView = self.tableView;

    switch(type) {

        case NSFetchedResultsChangeInsert:
            [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]
                       withRowAnimation:UITableViewRowAnimationFade];
            break;

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

        case NSFetchedResultsChangeUpdate:
            [self configureCell:[tableView cellForRowAtIndexPath:indexPath]
                  atIndexPath:indexPath];
            break;

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


- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
    [self.tableView endUpdates];
}

使用此代码，默认分组样式表视图通过背景视图更改动画很好地更新其单元格:删除第一个单元格时，第二个单元格成为第一个单元格，其顶角从方形变为圆形，等等.

With this code, default grouped styled table view updates its cells nicely with background view change animations: when deleting the first cell, the second cell becomes the first with its top corners changing from square to round, and things like that.

然而，对于具有自定义backgroundView的单元格，表格视图不会为我们做相同的背景视图转换.所以我们会看到这样的事情:

However, for cells with custom backgroundView，table view does not do the same background view transitions for us. So we'll see things like this:

删除第一行前

删除第一行后

如何通过适当的背景视图更新恢复漂亮的动画?

How can I restore the nice animation with proper background view updates?

推荐答案

没有内置的简单方法可以在分组的 tableview 上使用自定义单元格背景来管理单元格动画.

There is no built in, simple way to manage the cell animations with a custom cell background on a grouped tableview.

您要么维护一个背景需要重绘的单元格列表，然后使用 [cell.backgroundView setNeedsDisplay]

You either maintain a list of cells whose background needs redrawing then use [cell.backgroundView setNeedsDisplay]

或者你可以考虑屏蔽 tableview.所以你有一个单元格背景，但它们被剪裁见 UITableView 上的圆角

Or you could consider masking the tableview. So you have one cell background but they are clipped see Round corners on UITableView

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