我有一个SCNNode,并且我使用这种方法从.dae文件中应用了几何体:
func addNode(gridPosition: SCNVector3, row: Int, gamePlaneHeight: Float, sceneArray: [ObjectInfo]) -> SCNNode {
// Create a material using the model_texture.tga image
let carMaterial = SCNMaterial()
carMaterial.diffuse.contents = UIImage(named: "assets.scnassets/Textures/model_texture.tga")
carMaterial.locksAmbientWithDiffuse = false
// Create a clone of the Car node of the carScene - you need a clone because you need to add many cars
var carNode: SCNNode!
let randomNumb = AppDelegate().randRange(0, upper: sceneArray.count - 1)
let selectedObject = sceneArray[randomNumb]
carNode = selectedObject.objectscene.rootNode.childNodeWithName(selectedObject.objectname, recursively: false)!.clone() as SCNNode
carNode.scale = SCNVector3(0.5, 0.5, AppDelegate().randomBetweenNumbers(0.8, secondNum: 2.2))
carNode.name = selectedObject.objectname
carNode.position = gridPosition
carNode.position.y = carNode.position.y + gamePlaneHeight
// Set the material
carNode.geometry?.firstMaterial = carMaterial
return carNode
}
该方法大部分时间都有效,但偶尔会在线路上崩溃
carNode.geometry?.firstMaterial = carMaterial
错误
fatal error: unexpectedly found nil while unwrapping an Optional value
warning: could not load any Objective-C class information from the dyld shared cache. This will significantly reduce the quality of type information available.
我不明白为什么,因为大部分时间都有效。
答案 0 :(得分:2)
carNode
由selectedObject.objectname
构建。
如果场景中不存在selectedObject.objectname
,则childNodeWithName
将返回nil
。因为carNode
是一个隐式解包的可选项,Swift会尝试解包nil
并崩溃。
您应该carNode
选择var carNode: SCNNode?
}或添加if carNode == nil { ... }
之类的测试,并尝试调整您的输入(selectedObject
)是什么以及它为什么会这样做?不正确。