swift - 在 Swift 3 中创建一个 UnsafeMutablePointer> 参数

Question

Accelerate 框架的 Swift 签名 vDSP_biquadm()函数包括 UnsafeMutablePointer<UnsafePointer<Float>> 的参数类型和 UnsafeMutablePointer<UnsafeMutablePointer<Float>> .

如何在 Swift 3 中声明和创建此类类型，然后使用对多个类型为 [Float] 的 Swift 数组的引用来填充这些指针数组？ .

Answer 1

当您需要为 UnsafeMutablePointer<T> 传递多个值时参数，需要声明一个类型为[T]的变量(又名 Array<T> )并将其作为 inout 参数传递。在你的情况下 T是UnsafeMutablePointer<Float> .

所以，如果您想从 [Float] 开始，你可能需要这样写:

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)
    }
}