Typecast UnsafeMutablePointer<Void> to UnsafeMutablePointer<#Struct type#>

Question

I created a struct in Swift called RGB, simple enough:

struct PixelRGB {
    var r: CUnsignedChar = 0
    var g: CUnsignedChar = 0
    var b: CUnsignedChar = 0

    init(red: CUnsignedChar, green: CUnsignedChar, blue: CUnsignedChar) {
        r = red
        g = green
        b = blue
    }
}

And I have a pointer var imageData: UnsafeMutablePointer<PixelRGB>!.

I wish to malloc some space for this pointer, but malloc returns UnsafeMutablePointer<Void> and I cannot cast it like below:

imageData = malloc(UInt(dataLength)) as UnsafeMutablePointer<PixelRGB> // 'Void' is not identical to `PixelRGB`

Anyway to solve this? Thank you for your help!

Answer 1

I think what you want to say is something like this:

imageData = UnsafeMutablePointer<PixelRGB>.alloc(dataLength)

Answer 2

Have you tried the following?

imageData = unsafeBitCast(malloc(UInt(dataLength)), UnsafeMutablePointer<PixelRGB>.self)

Ref: Using Legacy C APIs with Swift