NSOutlineView reloadItem：没有效果 [英] NSOutlineView reloadItem: has no effect

问题描述

我试图在基于视图的 NSOutlineView 中释放一些压力，为此我更改了单个项目属性，我最初使用<$ c $ c> [myOutlineView reloadData] 。

<但它从不调用 - （NSView *）outlineView：（NSOutlineView *）ov viewForTableColumn：（NSTableColumn *）tableColumn item：（id）item

   - （void）reloadOutlineViewObject 
 {
 // [myOutlineView reloadData]; //重新加载数据只是罚款，但是ressource-hungry 
 NSLog（@％d，[myOutlineView rowForItem：myOutlineViewItem]; //确保我的对象是一个项目的outlineView，它是！
 [myOutlineView reloadItem：myOutlineViewItem]; 
} 
  

p>

UPDATE

正如评论中指出的，我的outlineView是基于视图的。

UPDATE 2

尝试一些东西让我意识到我重载的对象是一个二级对象（对象树）调用 reloadItem：firstLevelObject reloadChildren：YES 可以工作。

有可能我们只能调用reloadItem：on第一级对象？在我的情况下，这将是非常低效的（我只有一个两级项目和大量的第二级）。

  nil  - > firstLevelA  - > secondLevel1 
  - > secondLevel2 
  - > firstLevelB  - > secondLevel3 
  - > secondLevel4 
  
 
 
 
在同一时间尝试子类化NSOutlineView并重写 reloadItem：。
 
 
 
 UPDATE 3 
 
 
 
我看了一下 NSOutlineView在Cocotron 获得开始，并认为我需要编写的代码覆盖reloadItem将安静沉重。任何人都要确认？
解决方案
我遇到了同样的问题与基于视图的大纲视图，其中调用 -reloadItem：似乎只是不做任何事情。这肯定看起来像一个大bug，虽然文档没有明确说， reloadItem 将重新获取该行的视图。
 
 
 
我的解决方法是调用 NSTableView 的 -reloadDataForRowIndexes：columnIndexes：预期，触发对该项的 -outlineView：viewForTableColumn：item：委托方法的调用。您可以通过调用 -rowForItem：并传入要重新加载的项目来获取需要重新加载的行。
 
I'm trying to release some strain on a view-based NSOutlineView for which I changed a single item property and which I initially reloaded just fine using [myOutlineView reloadData].

I tried  [myOutlineView reloadItem: myOutlineViewItem] but it never calls - (NSView *)outlineView:(NSOutlineView *)ov viewForTableColumn:(NSTableColumn *)tableColumn item:(id)item and consequently the data is not updated.
-(void)reloadOutlineViewObject
{
    //[myOutlineView reloadData];   //Reload data just fines but is ressource-hungry
    NSLog(@"%d",[myOutlineView rowForItem:myOutlineViewItem]; //Making sure my object is an item of the outlineView, which it is !
    [myOutlineView reloadItem:myOutlineViewItem];   
}
Am I missing something here ?

UPDATE

As pointed out in the comments, my outlineView is view-based.

UPDATE 2

Trying out some stuffs made me realized that the object I am reloading is a second-level object (cf object tree) and calling reloadItem:firstLevelObject reloadChildren:YES does work.

Would it be possible that we can only call reloadItem: on first-level object ? That would be highly inefficient in my case (I only have one two level item and plenty of second level) !
nil ->firstLevelA ->secondLevel1
                  ->secondLevel2
    ->firstLevelB ->secondLevel3
                  ->secondLevel4
Gonna try to subclass NSOutlineView and rewrite reloadItem: in the mean time.

UPDATE 3

I took a look at NSOutlineView in Cocotron to get start and felt that the code I needed to write to overwrite reloadItem would be quiet heavy. Anyone to confirm ?
解决方案
I encountered this same problem with a view-based outline view, where calling -reloadItem: seems to just not do anything. This definitely seems like a big bug, though the documentation doesn't explicitly say that reloadItem will reacquire the views for that row.

My workaround was to call NSTableView's -reloadDataForRowIndexes:columnIndexes: instead, which seems to work as expected, triggering a call to the -outlineView:viewForTableColumn:item: delegate method for just that item. You can get the row that needs to be reloaded by calling -rowForItem: and passing in the item you want to reload.

                        
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