添加了自定义的UIView到SCNNode不能正常显示

Question

我想用一个的UILabel添加自定义的UIView到SCNNode（使用SceneKit和ARKit）。

我用SCNPlane用含有创建的UIView的层SCNMaterial。然后我初始化新SCNNode并将其添加到场景中。首先，我试过的UIView在Interface Builder创建，这是行不通的。所以我决定创建的UIView programmaticaly。

class InfoPlaneNodeView: UIView {
    var elevationLabel: UILabel

    override init(frame: CGRect) {
        elevationLabel = UILabel(frame: frame)
        super.init(frame: frame)
        backgroundColor = UIColor.white
        layer.cornerRadius = 20

        elevationLabel.translatesAutoresizingMaskIntoConstraints = false
        elevationLabel.textColor = UIColor.black
        elevationLabel.text = "333m"
        addSubview(elevationLabel)

        elevationLabel.centerXAnchor.constraint(equalTo: centerXAnchor).isActive = true
        elevationLabel.centerYAnchor.constraint(equalTo: centerYAnchor).isActive = true
    }
}

class InfoViewPlaneNode: SCNNode {
    init(planeWidth: CGFloat, planeHeight: CGFloat) {
        let material = SCNMaterial()
        let infoPlaneNodeView = InfoPlaneNodeView(frame: CGRect(x: 0, y: 0, width: 200, height: 100))
        material.diffuse.contents = infoPlaneNodeView.layer
        material.transparency = 0.7
        material.lightingModel = .constant
        material.isDoubleSided = true

        let plane = SCNPlane(width: planeWidth, height: planeHeight)
        plane.materials = [material]
        super.init()
        self.geometry = plane
        self.position = SCNVector3(0, 3, 0)
    }
}

当我运行的所有代码，我只看到白色的UIView没有的UILabel。我想这个代码，而无需SceneKit，一切工作正常。在哪里的问题？谢谢

Answer 1

有一次，我遇到这种情况。由于观点没有任何视图控制器的一部分，你必须手工绘制它：

view.setNeedsDisplay()
view.displayIfNeeded()