在Swift 3中创建UnsafeMutablePointer<UnsafeMutablePointer<Float>>参数

Question

加速框架vDSP_biquadm()函数的Swift签名包括UnsafeMutablePointer<UnsafePointer<Float>>和UnsafeMutablePointer<UnsafeMutablePointer<Float>>的参数类型。

如何在Swift 3中声明和创建这些类型，然后用对几个[Float]类型Swift数组的引用填充这些指针数组。

Answer 1

当您需要为UnsafeMutablePointer<T>参数传递多个值时，您需要声明一个类型为[T] (又名Array<T>)的变量，并将其作为inout参数传递。在您的例子中，T是UnsafeMutablePointer<Float>。

因此，如果您想从[Float]开始，您可能需要编写如下内容：

let input: [Float] = [/*...*/]
var output: [Float] = Array(repeating: 0, count: outputTotalSize)
input.withUnsafeBufferPointer {inBuf in
    let inputPtr = inBuf.baseAddress!
    output.withUnsafeMutableBufferPointer {outBuf in
        let outputPtr = outBuf.baseAddress!
        var pInputs: [UnsafePointer<Float>] = [inputPtr,/*...*/]
        var pOutputs: [UnsafeMutablePointer<Float>] = [outputPtr/*...*/]
        vDSP_biquadm(setup, &pInputs, inStride, &pOutputs, outStride, length)
    }
}