从NSOutlineView或NSTreeController中删除显示中的NSElements

Question

如何在NSOutlineView中绑定到由NSXMLDocument驱动的NSTreeController，只显示一些NSElements(相同类型(而不显示其他NSElements？

感谢

Answer 1

要隐藏某些元素，必须对NSXMLElement进行子类化。它的目的是测试元素的一个子元素是否是要隐藏的子元素之一，并将其从children数组中删除：

class ICoderElement:NSXMLElement{
    ///List of elements names to remove
    let nodeElementsNamesToRemove = ["title", "code"]
    override var children: [AnyObject]? {
        //get the array with all the children
        var superChildren = super.children
        //Cast the array of children to its true self
        if var trueSuperChildren = superChildren as? [NSXMLNode] {
            //Test if the array isn't empty to don't iterate over it
            if trueSuperChildren.count > 0 {
                //Iterate each of them
                for var index = 0; index < trueSuperChildren.count; index++ {
                    let node = trueSuperChildren[index]
                    //If any it's of NSXMLElement class unwarps it's name and...
                    if let nodeElement = node as? NSXMLElement, let nodeName = nodeElement.name {
                        //..tests if it's name it's o the list of elements to remove
                        //change to nodeElementsNamesToRemove.contains(nodeName) in swift2
                        if contains(nodeElementsNamesToRemove, nodeName) {
                            //Remove the child NSXMLElement from the array
                            trueSuperChildren.removeAtIndex(index)
                            //reduce the index as the array 1 less element
                            index = index - 1
                        }
                    }
                }
            }
            //returns the array without the selected elements
            return trueSuperChildren
        }
        return superChildren
    }
}

要使用此类，还必须将NSXMLDocument子类化，以便用NSXMLElement:替换

class ICoderXMLDocument:NSXMLDocument {
    override class func replacementClassForClass(cls: AnyClass) -> AnyClass! {
        //Replace NSXMLElement by ICoderElement
        if cls === NSXMLElement.self {
            return ICoderElement.self
        }
        return cls
    }
}

今后应谨慎使用childCount。它仍然会返回XML文件中的子节点数。

因为这些元素只是隐藏的，所以仍然可以用elementsForName这样的函数。