ios - Swift: "Must call a designated initializer of the superclass"错误，即使代码正在这样做

Question

目标是子类化 SCNNode。根据class docs , init(geometry geometry: SCNGeometry?) 是一个指定的初始化器(没有列出 convenience 关键字)，所以这段代码不是调用其父类(super class)的指定初始化器吗？

为什么 Xcode 显示以下错误？

Must call a designated initializer of the superclass SCNNode

class PreviewNode: SCNNode {
    // Constants
    let PreviewNodeColor = gRedColor
    let Size = CGFloat(1.0)
    let ChamferRadius = CGFloat(0.0)

    override init() {
        let previewBox = SCNBox(width: Size, height: Size, length: Size, chamferRadius: ChamferRadius)
        previewBox.firstMaterial!.diffuse.contents = PreviewNodeColor
        previewBox.firstMaterial!.transparency = 0.2
        previewBox.firstMaterial!.specular.contents = UIColor.whiteColor()
        super.init(geometry: previewBox)
    }
}

Answer 1

问题在于您还试图在调用 self.init() 之前访问您的 PreviewNode 属性

像这样尝试:

Xcode 8 GM • Swift 3

class PreviewNode: SCNNode {
    let previewNodeColor: UIColor = .red
    let size: CGFloat = 1
    let chamferRadius: CGFloat = 0
    convenience override init() {
        self.init()
        let previewBox = SCNBox(width: size, height: size, length: size, chamferRadius: chamferRadius)
        previewBox.firstMaterial?.diffuse.contents = previewNodeColor
        previewBox.firstMaterial?.transparency = 0.2
        previewBox.firstMaterial?.specular.contents = UIColor.white
        self.geometry = previewBox
    }
}