设置和维护 NSTableView 的第一个 SortDescriptor

发布于 2024-12-19 22:23:09 字数 522 浏览 0 评论 0原文

我有一个 NSTableView，其列绑定到 NSArrayController。

表格视图显示电子邮件列表：

如果未读则标记
主题
附件大小

用户可以单击“附件大小”列对列表进行排序，但我希望表格始终首先按“未读”标记排序 以便未读消息始终保留在列表顶部。

我没有将数组控制器的排序描述符绑定到任何东西，但是通过单击表列，表排序可以神奇地工作（为什么？）。有什么方法可以拦截设置数组控制器的排序描述符并首先插入“未读”排序描述符？

按附件大小排序的表格示例：

UNREAD▼ SUBJECT ATTACHMENT SIZE▼
------  ------- ------------------
  yes   Hello.. 110kb
  yes   Test...  90kb

  no    Foobar  200kb
  no    Hey     100kb
  no    Test2    10kb

原文

I have an NSTableView with columns bound to an NSArrayController.

The table view shows a list of email messages:

Flag if unread
Subject
Attachment size

The user can click on the Attachment Size column to sort the list, but I would like the table to always be sorted by the "unread" flag first so that the unread messages always remain at the top of the list.

I did not bind the Array Controller's sort descriptors to anything, yet table sorting works magically by clicking on the table columns (why?). Is there some way I can intercept setting the Array Controller's sort descriptors and insert the "Unread" sort descriptor first?

Example of a table sorted by attachment size:

UNREAD▼ SUBJECT ATTACHMENT SIZE▼
------  ------- ------------------
  yes   Hello.. 110kb
  yes   Test...  90kb

  no    Foobar  200kb
  no    Hey     100kb
  no    Test2    10kb

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横笛休吹塞上声 2024-12-26 22:23:09

好吧，它“正常工作”的原因是因为表列在其绑定的 NSArrayController 上调用 setSortDescriptors: 。

假设你希望表格保持可排序，但你总是想按“未读”排序，这就是我的做法：

首先，子类 NSArrayController 并覆盖 arrangeObjects：

- (NSArray *)arrangeObjects:(NSArray *)objects {

    NSMutableArray *oldSorted = [[super arrangeObjects:objects] mutableCopy];
    NSMutableArray *newSorted = [NSMutableArray arrayWithCapacity:[oldSorted count]];

    for (id anObject in oldSorted)
        if ([[anObject valueForKey:@"isUnread"] boolValue])
            [newSorted addObject:anObject];

    [oldSorted removeObjectsInArray:newSorted];
    [newSorted addObjectsFromArray:oldSorted];
    [oldSorted release];

    return newSorted;
}

这会将未读消息放在“顶部”（数组的开头）。我不确定这是最有效的排序算法，但我相信这是正确的方法。

Well, the reason it "just works" is because the table columns call setSortDescriptors: on their bound NSArrayController.

Assuming you want the table to remain sortable, but you always want to sort by "unread", this is how I would go about it:

First, subclass NSArrayController and override arrangeObjects:

- (NSArray *)arrangeObjects:(NSArray *)objects {

    NSMutableArray *oldSorted = [[super arrangeObjects:objects] mutableCopy];
    NSMutableArray *newSorted = [NSMutableArray arrayWithCapacity:[oldSorted count]];

    for (id anObject in oldSorted)
        if ([[anObject valueForKey:@"isUnread"] boolValue])
            [newSorted addObject:anObject];

    [oldSorted removeObjectsInArray:newSorted];
    [newSorted addObjectsFromArray:oldSorted];
    [oldSorted release];

    return newSorted;
}

This puts unread messages at the "top" (beginning of array). I'm not sure this is the most efficient sorting algorithm, but I believe it's the correct way to go about it.

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一页 2024-12-26 22:23:09

我认为您可以在 awakeFromNib 期间在数组控制器上设置一个 sortDescriptors 数组。无需强制 arrangeObjects:，此功能完全内置。

- (void)awakeFromNib {
    [super awakeFromNib];
    NSSortDescriptor *unreadSorter = [[NSSortDescriptor sortDescriptorWithKey:@"isUnread" ascending:NO)] autorelease];
    NSArray *arrayOfSortDescriptors = [NSArray arrayWithObject:unreadSorter];
    [self setSortDescriptors:arrayOfSortDescriptors];
}

当您单击列标题时，列仍将保持可排序。

I think that you can just set an array of sortDescriptors on your array controller during awakeFromNib. No need to force arrangeObjects:, this functionality totally built in.

- (void)awakeFromNib {
    [super awakeFromNib];
    NSSortDescriptor *unreadSorter = [[NSSortDescriptor sortDescriptorWithKey:@"isUnread" ascending:NO)] autorelease];
    NSArray *arrayOfSortDescriptors = [NSArray arrayWithObject:unreadSorter];
    [self setSortDescriptors:arrayOfSortDescriptors];
}

The columns will still remain sortable when you click the column header.

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