ios - 无法使用类型为 'UnsafeMutablePointer' 的参数列表调用类型为 '(UnsafeMutableRawPointer!)' 的初始值设定项

Question

第 5 行的这种关联对应用程序的成功没有贡献。但老实说，我不明白那一刻发生了什么。

Overloads for ÜnsafeMutablePointer exist with partially matching parameter list: (RawPointer).

但这是什么意思呢？谢谢

override func buffer(withCsound cs: CsoundObj) -> Data {
            let length    = Int(AKSettings.shared().numberOfChannels) *
                            Int(AKSettings.shared().samplesPerControlPeriod) * 4
            let num       = length / 4
            let floats    = UnsafeMutablePointer<Float>(malloc(length))

            /* The phase and amplitude are different for each line to get a nice
             * gimmick. */
            let phase     = (self.amplifier + 0.8) / 1.8

            for i in 0 ... num - 1 {
                /* The amplitude is placed within the for-loop because it can fade
                 * to a slightly different value during one plot refresh. */
                let amplitude = self.amplifier * self.amplitude

                /* It is incredibly important that `time` and `phase` aren't
                 * multiplied with the frequency or else it will bump at each
                 * frequency change. */
                var t = (time + Double(i) / Double(num) * self.frequency + phase)

                floats[i] = Float(sin(t * 2 * 3.14))

                /* It is multiplied with a "regular" 0.5 Hz sine to get both ends
                 * to fade out nicely. It's sort of a simplistic window function. */
                t = Double(i) / Double(num)
                floats[i] *= Float(sin(t * 1 * 3.14) * amplitude)
                floats[i] *= 1 - pow(1 - Float(i) / Float(num), 2.0)

                time += self.frequency / 44100 / 2

                /* Fade smoothly to the next frequency and amplitude. */
                self.frequency += (nextFrequency - self.frequency) / 44100.0 / 4.0
                self.amplitude += (nextAmplitude - self.amplitude) / 44100.0 / 2.0
            }

            /* We keep the time between 0 and 1 to make sure it never overflows /
             * loses the necessary precision. */
            time = fmod(time, 1.0)

            return Data(bytesNoCopy: UnsafeMutablePointer<UInt8>(floats), count: length, deallocator: .free)
        }

Answer 1

你可以找到一些类似的文章搜索错误信息。

例如:How to use UnsafeMutablePointer in Swift 3?

你最好阅读MIGRATING TO SWIFT 3 , 特别是 this article .

---

具体到您的情况。

改变这一行:

let floats    = UnsafeMutablePointer<Float>(malloc(length))

到:

let rawBytes  = malloc(length)!
let floats    = rawBytes.assumingMemoryBound(to: Float.self)

并更改最后一行:

return Data(bytesNoCopy: UnsafeMutablePointer<UInt8>(floats), count: length, deallocator: .free)

到:

return Data(bytesNoCopy: rawBytes, count: length, deallocator: .free)

---

选项 2。

更改行 let floats = UnsafeMutablePointer<Float>(malloc(length))到:

var data = Data(count: length)
data.withUnsafeMutableBytes {(floats: UnsafeMutablePointer<Float>) in

并将最后一行更改为:

}
return data

(它们之间的所有行都包含在闭包 {(floats: UnsafeMutablePointer<Float>) in ...} 中。)