Arrays 为什么ASTextNode不显示？

我不明白为什么不显示文本

导入UIKit 导入异步显示工具包

类ViewController:ASViewController{

init() {
    super.init(node: ASDisplayNode())
    let text = ASTextNode()
    let attrs = [NSAttributedStringKey.font: UIFont(name: "HelveticaNeue", size: 12.0)!]
    let string = NSAttributedString(string: "Hello World!", attributes: attrs)
    text.attributedText = string
    self.node.addSubnode(text)
}
required init?(coder aDecoder: NSCoder) {
    super.init(node: ASDisplayNode.init())
}

}

导入UIKit
导入异步显示工具包
类ViewController:ASViewController{
init（）{
super.init（节点：LayoutExampleNode（））
}
必需的初始化？（编码器aDecoder:NSCoder）{
super.init（节点：ASDisplayNode.init（））
}
}
类布局ExampleNode:ASDisplayNode{
重写所需的init（）{
super.init（）
AutomaticallyManageSubNodes=true
背景颜色=白色
}
}
扩展布局ExampleNode{
重写func LayoutSpechatFits（uConstrainedSize:ASSizeRange）->ASLayoutSpec{
让someVerticalStack=ASStackLayoutSpec.vertical（）
someVerticalStack.style.flexShrink=1.0
someVerticalStack.style.flexGrow=1.0
让text=ASTextNode（）
let attrs=[NSAttributedStringKey.font:UIFont（名称：“HelveticaNeue”，大小：12.0）！]
let string=NSAttributedString（字符串：“Hello World！”，属性：attrs）
text.attributedText=字符串
someVerticalStack.children=[文本]
让someVerticalStackSpec=ASStackLayoutSpec（方向：。水平，
间距：40，
辩护内容：。开始，
对齐项目：。中心，
子项：[someVerticalStack]）
返回ASInsetLayoutSpec（插图：UIEdgeInsets（顶部：0，左侧：10，底部：0，右侧：10），子项：someVerticalStackSpec）
}
}

由于您不需要显示该节点，请尝试阅读文档：

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    // Override point for customization after application launch.
    let window = UIWindow(frame: UIScreen.main.bounds)
    window.backgroundColor = UIColor.cyan
    window.rootViewController = ViewController()
    window.makeKeyAndVisible()
    self.window = window
    return true
}

import UIKit
import AsyncDisplayKit

class ViewController: ASViewController<ASDisplayNode>  {
    init() {
    super.init(node: LayoutExampleNode())
}
required init?(coder aDecoder: NSCoder) {
    super.init(node: ASDisplayNode.init())
}
}

class LayoutExampleNode: ASDisplayNode {
override required init() {
    super.init()
    automaticallyManagesSubnodes = true
    backgroundColor = .white
}

}

extension LayoutExampleNode {

override func layoutSpecThatFits(_ constrainedSize: ASSizeRange) -> ASLayoutSpec {
    let someVerticalStack = ASStackLayoutSpec.vertical()
    someVerticalStack.style.flexShrink = 1.0
    someVerticalStack.style.flexGrow = 1.0

    let text = ASTextNode()
    let attrs = [NSAttributedStringKey.font: UIFont(name: "HelveticaNeue", size: 12.0)!]
    let string = NSAttributedString(string: "Hello World!", attributes: attrs)
    text.attributedText = string

    someVerticalStack.children = [text]

    let someVerticalStackSpec = ASStackLayoutSpec(direction: .horizontal,
                                            spacing: 40,
                                            justifyContent: .start,
                                            alignItems: .center,
                                            children: [someVerticalStack])

    return ASInsetLayoutSpec(insets: UIEdgeInsets(top: 0, left: 10, bottom: 0, right: 10), child: someVerticalStackSpec)
}
}