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如何将NSTreeController、NSOutlookView和核心数据与“不可见”根项一起使用?

nstreecontroller nsoutlineview core-data macos cocoa

Rob Keniger · 技术社区 · 16 年前

parent 和 children NSTreeController NSOutlineView .

parent == nil

isRootItem

Node 1
|
+-Node 2
  |   |
  |   +-Node 5
  |
  Node 3
  |
  Node 4

大纲视图应如下所示:

_{(来源:

menumachine.com}

YES 为了 NO .

parent.isRootItem == 1

2 回复 | 直到 7 年前

Rob Keniger 16 年前

我最终做的是将NSTreeController子类化并覆盖 -insertObject:atArrangedObjectIndexPath: 如果要插入的对象是在树的顶层插入的,则直接将父对象设置为我的根对象。这似乎工作可靠。

- (void)insertObject:(id)object atArrangedObjectIndexPath:(NSIndexPath *)indexPath
{
    NodeObject* item = (NodeObject*)object;
    //only add the parent if this item is at the top level of the tree in the outline view
    if([indexPath length] == 1)
    {
        //fetch the root item
        NSEntityDescription* entity = [NSEntityDescription entityForName:@"NodeObject" inManagedObjectContext:[self managedObjectContext]];
        NSFetchRequest* fetchRequest = [[NSFetchRequest alloc] init]; //I'm using GC so this is not a leak
        [fetchRequest setEntity:entity];
        NSPredicate* predicate = [NSPredicate predicateWithFormat:@"isRootItem == 1"];
        [fetchRequest setPredicate:predicate];

        NSError* error;
        NSArray* managedObjects = [[self managedObjectContext] executeFetchRequest:fetchRequest error:&error];

        if(!managedObjects)
        {
            [NSException raise:@"MyException" format:@"Error occurred during fetch: %@",error];
        }

        NodeObject* rootItem = nil;
        if([managedObjects count])
        {
            rootItem = [managedObjects objectAtIndex:0];
        }
        //set the item's parent to be the root item
        item.parent = rootItem;
    }
    [super insertObject:object atArrangedObjectIndexPath:indexPath];
    //this method just sorts the child objects in the tree so they maintain their order
    [self updateSortOrderOfModelObjects];
}