Re: NSOutline and NSTreeController using bindings
Re: NSOutline and NSTreeController using bindings
- Subject: Re: NSOutline and NSTreeController using bindings
- From: Hrishikesh Murukkathampoondi <email@hidden>
- Date: Tue, 12 Oct 2010 19:22:44 +0530
I moved the code populating myListRoot to the "-init" method of MyDocument.m and now it works. I was earlier populating it in "-awakeFromNib".
I am so tried putting it back in -awakeFromNib followed by a call to [mOutlineView reloadData] - but this did not work.
So I have my NSOutlineView showing me the text stored in my data root tree. But cant explain the above behavior.
Thanks
Hrishi
On 12-Oct-2010, at 6:59 PM, Hrishikesh Murukkathampoondi wrote:
> Thanks for the response. I am still having a little trouble. Here is what I have done. I have set the keypaths and bindings of the NSTreeController and NSOutlineView as below.
>
> myListRoot is a NSMutableArray containing NSTreeNode objects. I point the content array binding of the NSTreeController to this variable. My tree is only one level deep for now (I am still testing it). I add nodes to my tree in this fashion:
>
> NSTreeNode *tn = [NSTreeNode treeNodeWithRepresentedObject:[NSString stringWithString:@"History"]];
> [myListRoot addObject:tn];
>
> MyDocument is KVC compliant with regard to myListRoot. After adding nodes I traversed the tree (simple for loop) and printed contents to check the data is correctly added.
>
> I made the following bindings -
>
> NSTreeController:
> Key paths:
> --------------
> Children: childNodes
>
> Since the nodes in the tree are objects of type NSTreeNode childNodes is the correct method to return children of a given node.
>
> Bindings:
> ------------
> Content Array: File's Owner myListRoot
>
>
> I believe with the above bindings I have correctly tied the NSTreeController to my data. Is this correct?
>
> I have made the following bindings in IB to bind elements in NSOutlineView to the NSTreeController.
>
> NSOutlineView:
> Bindings:
> -----------
> Controller Key: arrangedObjects
> Selection Index Paths: selectionIndexPaths
>
> Table Column Bindings:
> ---------------------
> Controller Key: arrangedObjects
> Model Key Path: representedObject
>
> I expect that the table will send "representedObject" message to each NSTreeNode object to get the string to be printed in each cell.
>
> When I run this I dont see the column in NSOutlineView populated. What am I doing incorrectly?
>
> Hrishi
>
>
> On 11-Oct-2010, at 1:50 AM, email@hidden wrote:
>
>>
>> Regards
>>
>>
>>
>> On 10 Oct 2010, at 19:55, Hrishikesh Murukkathampoondi wrote:
>>>
>>> NSOutlineView bindings -
>>> 1. "Content" bound to NSTreeController's "arrangedObjects"
>>> 2. "Selection Index Paths: to NSTreeController's "selectionIndexPaths"
>>>
>>> NSTableColumn bindings:
>>> 3. "Value" is bound to arrangedObjects.name
>>>
>> These look okay.
>>>
>>> I have read the class reference for NSTreeController and NSOutlineView but I still dont understand how the above works. Foe example, how does the NSOutlineView know which values are leaves?
>>>
>>> NSOutlineView class ref document describes how to implement the data source if using conventional data sources. How does it work with bindings?
>>>
>>> The above "special" format for the contents array is not discussed any where.
>>>
>> The example creates a single node with three children.
>> The 'special format' you refer is documented in NSTreeController. Its not the array that is important, it's the objects within in it.
>> In the example above we must presume that NSTreeController -childrenKeyPath has been set to @"children" (this may have been done in IB).
>> This way the controller knows which method to call to traverse the tree (there is also a -leafKeyPath method).
>>
>> The contents array is an array of objects each of which acts as the root for a branch.
>> In this case the object is a single NSDictionary object.
>> This will be queried using -valueForKey:/-valueForKeyPath: which will ultimately invoke -objectForKey: on the dictionary.
>>
>> Basically you supply a readymade tree and bind it to the NSTreeController.
>> Although an NSDictionary can be used for this purpose NSTreeNode is supplied specifically for this purpose.
>> Create an array of NSTreeNode instances that will act as your roots.
>> Then add your children to the roots as further NSTreeNode instances.
>> Your model object can be supplied as the -representedObject in which case the binding key path typically looks like @"arrangedObjects.representedObject.name"
>>
>> An item in an NSOutlineView will be represented as an NSTreeNode (see the 10.5 release notes for this essential fact).
>> However the tree that is returned is the NSOutlineView's currently displayed tree.
>> Your NSTreeNode (or whatever representation you have employed) instance is the item's representedObject.
>> Hence to get to your model data you would invoke:
>>
>> NSTreeNode *outlineNode = [outlineView itemAtRow:row];
>> NSTreeNode *myNode = [outlineNode representedObject];
>> id myNodelData = [myNode representedObject];
>>
>> HTH
>>
>> Jonathan Mitchell
>>
>> Developer
>> Mugginsoft LLP
>> http://www.mugginsoft.com
>
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