cocoa - 从 NSOutlineView 或 NSTreeController 中移除 NSElements

Question

我如何才能在 NSOutlineView 中绑定到由 NSXMLDocument 驱动的 NSTreeController，只显示一些 NSElement（相同类型）而不显示其他？

谢谢

Answer 1

要隐藏某些元素，NSXMLElement必须对其进行子类化。其目的是测试元素的其中一个子元素是否是要隐藏的元素之一并将其从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，NSXMLDocument还必须对其进行子类化，以便可以将其替换为NSXMLElement：

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childCount应慎用。它仍然会从 XML 文件返回子节点的数量。

因为这些元素只是隐藏的，所以仍然可以使用elementsForName.