Ios ARKIT：在一个SCNNode与另一个SCNNode之间画线时，观察滞后

我画了线，并创建了一个具有尺寸的长方体。在iPhone8及以上版本上面临滞后问题，但在iPhone7上运行平稳

用于更新行：

fileprivate func updateLine(_ line: SCNNode, from position: SCNVector3, distance: Float, axis: SCNVector3.Axis) {
        guard let box = line.geometry as? SCNBox else {
            fatalError("Tried to update something that is not a line")
        }
        
        let absDistance = CGFloat(abs(distance))
        let offset = distance * 0.5
        switch axis {
        case .x:
            box.width = absDistance
            line.position = position + SCNVector3(x: offset, y: 0, z: 0)
        case .y:
            box.height = absDistance
            line.position = position + SCNVector3(x: 0, y: offset, z: 0)
        case .z:
            box.length = absDistance
            line.position = position + SCNVector3(x: 0, y: 0, z: offset)
        }
    }

iphone7:

fileprivate func updateLine(_ line: SCNNode, from position: SCNVector3, distance: Float, axis: SCNVector3.Axis) {
        guard let box = line.geometry as? SCNBox else {
            fatalError("Tried to update something that is not a line")
        }
        
        let absDistance = CGFloat(abs(distance))
        let offset = distance * 0.5
        switch axis {
        case .x:
            box.width = absDistance
            line.position = position + SCNVector3(x: offset, y: 0, z: 0)
        case .y:
            box.height = absDistance
            line.position = position + SCNVector3(x: 0, y: offset, z: 0)
        case .z:
            box.length = absDistance
            line.position = position + SCNVector3(x: 0, y: 0, z: offset)
        }
    }

中央处理器：48%

内存：199MB

FPS:60

帧渲染时间：1.9毫秒

iPhone 8 Plus: 中央处理器：48%

内存：236MB

GPU:4.5

FPS:60

帧渲染时间：16.6毫秒

---

项目中没有内存泄漏。

我在iPhone8 plus和更高版本上遇到了滞后问题，但在iPhone7上绘制的线条工作顺利，所以我实现了

 // Show statistics such as fps and timing information
        sceneView.showsStatistics = true

为了比较iPhone7和iPhone8 plus之间的差异，我注意到iPhone8 plus和更高版本需要18ms帧渲染时间，而iPhone7的帧渲染时间仅为1ms因此我将FPS从默认值60FPS减少

sceneView.preferredFramesPerSecond = 40

现在滞后的问题解决了