StackOverflow2013

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PONSOutlineView not updating
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copied!<p>I'm trying to hook up a view-based NSOutlineView to my model using an NSTreeController and bindings.</p> <p>My model consists of a main Node class (and subclasses of it). Every node can have 0 or more children. I'm storing the children in a C array (of Node objects) for performance reasons. I defined the <code>childrenKeyPath</code>, <code>countKeyPath</code> and <code>leafKeyPath</code> properties of my NSTreeController and implemented them in my Node class:</p> <pre><code>- (NSArray *)childNodes { return [NSArray arrayWithObjects:children_ count:childCount_]; } - (BOOL)nodeIsLeaf { return childCount_ < 1; } - (NSUInteger)childCount { return childCount_; } </code></pre> <p>When I add a new child, I call <code>[self willChangeValueForKey:@"childNodes"]</code> before and <code>[self didChangeValueForKey:@"childNodes"]</code> after inserting it into the C array.</p> <p>I set up the bindings as described in the documentation. (I bound the Content Object of the NSTreeController to my root Node. I bound the Content of the NSOutlineView to the NSTreeController's arrangedObjects. I also bound the NSTextField to the NSTableViewCell's objectValue.name property)</p> <p>The initial configuration (the root object and it's children) is loaded fine upon running the app. I can also add new children to the root object. </p> <p>However when I try to add a new child to any node (<em>except</em> the root) that has no children yet (no disclosure triangle) the NSOutlineView doesn't update (still no triangle). The new node is inserted into the model correctly and the will/didChangeValue messages are sent, but the NSTreeController doesn't bother examining the new children array. Logging the 3 keyPath functions above doesn't print anything in this case. </p> <p>If I close the parent and expand it again, then the nodes are reloaded, the disclosure triangle is shown and I can expand the node to see the new node I just added. Why doesn't the NSTreeController examine the changes, even though I sent the KVO messages when changing the children array? </p>

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