ios - 在 swift 中开设一个类中的类的成本是多少？

Question

我正在尝试在类中快速创建类，以便我可以更轻松地按类别访问变量。例如，我的渲染器有很多管道，因此能够转到 pipelines.<whateverPipelineINeed> 可能会很好。或者我的构建器可能有各种可以构建的管道，所以我可能想要 Builder.pipelines.<whatEverPipelineINeed>() 。

这促使我生成如下所示的代码

class Renderer: NSObject, MTKViewDelegate {
    let device:MTLDevice!
    let queue:MTLCommandQueue!
    let depth:MTLDepthStencilState!

    class Pipelines {
        static var defaultTriangles:MTLRenderPipelineState!
        static var fancyTriangles:MTLRenderPipelineState!
    }
    .......
}

或

class Builder {
    class func loadTexture(device: MTLDevice,
                           textureName: String) -> MTLTexture? {
        ...
    }

    class PipelineStates {
        class func blankTriangle(device: MTLDevice) -> MTLRenderPipelineState? {
            ...
        }

        class func fancyTriangle(device: MTLDevice) -> MTLRenderPipelineState? {
            ...
        }
    }
}

当然，这些管道远不止 2 个，我正在将这种模式用于其他对象。此外，不存在 = builder.() 的模式，因为某些对象经常初始化。此外，我还会使用可选类型检查编译中的错误。

这是一种快速做事的好方法吗？我应该了解与执行此类操作相关的低效率成本吗？

此外还有更好的方法吗？

Answer 1

你可以将它包装成枚举

public enum Pipeline {

    public enum PipelineName: String {
        case defaultTriangles
        case fancyTriangles
    }

    case defaultTriangles(MTLRenderPipelineState)
    case fancyTriangles(MTLRenderPipelineState)

    public var pipelineState: MTLRenderPipelineState {
        switch self {
        case .defaultTriangles(let pipeline): return pipeline
        case .fancyTriangles(let pipeline): return pipeline
        }
    }

    public init?(withDevice device: MTLDevice,
                 library: MTLLibrary,
                 pipelineName: PipelineName) {
        switch pipelineName {
        case .defaultTriangles:
            let pipelineDescriptor = MTLRenderPipelineDescriptor()
            // Set descriptor properties
            guard
                let pipelineState = try? device.makeRenderPipelineState(descriptor: pipelineDescriptor)
                else {
                    return
            }
            self = .defaultTriangles(pipelineState)
        case .fancyTriangles: 
            let pipelineDescriptor = MTLRenderPipelineDescriptor()
            // Set descriptor properties
            guard
                let pipelineState = try? device.makeRenderPipelineState(descriptor: pipelineDescriptor)
                else {
                    return
            }
            self = .defaultTriangles(pipelineState)
        }
    }

}

然后像这样初始化:

guard 
    let pipeline = Pipeline(withDevice: device,
                            library: library,
                            pipelineName: .defaultTriangles)
    else { return }
self.defaultPipeline = pipeline

然后当您需要渲染访问管道时，如下所示:

self.defaultPipeline.pipeline
/// Execute commands and set arguments / etc.

另外，使用中缀运算符定义渲染 channel 也很酷:

defaultTriangles |--> triangleComputationPipeline |--> fancyTriangles