Convert CFContextRef to mutable void pointer in swift?

Question

I'm trying to convert this objc code to swift:

CGContextRef contextRef = CGBitmapContextCreate(NULL,
                                                proposedRect.size.width,
                                                proposedRect.size.height,
                                                CGImageGetBitsPerComponent(imageRef),
                                                0,
                                                colorSpaceRef,
                                                (CGBitmapInfo)kCGImageAlphaPremultipliedFirst);
NSGraphicsContext *context = [NSGraphicsContext graphicsContextWithGraphicsPort:contextRef flipped:NO];

So far I ended up with this:

var bitmapContext: CGContext = CGBitmapContextCreate(data, UInt(proposedRect.width), UInt(proposedRect.height), CGImageGetBitsPerComponent(image), 0, colorSpace, CGBitmapInfo(CGImageAlphaInfo.PremultipliedFirst.toRaw()))
let context = NSGraphicsContext(graphicsPort: bitmapContext, flipped: false)

The problem is that CGBitmapContextCreate returns CGContext type and NSGraphicsContext initializer accepts graphicsPort as CMutableVoidPointer type. So how can I convert CGContext to CMutableVoidPointer?

related reverse type casting found here, but it didn't provide much help to me How to convert COpaquePointer in swift to some type (CGContext? in particular)

Answer 1

I ended up with the reinterpretCast function returning intermediate Int variable for the bitmapContext address.

var bitmapContext: CGContext = CGBitmapContextCreate(...)

let bitmapContextAddress: Int = reinterpretCast(bitmapContext)
let bitmapContextPointer: CMutableVoidPointer = COpaquePointer(UnsafePointer<CGContext>(bitmapContextAddress))
let context = NSGraphicsContext(graphicsPort: bitmapContextPointer, flipped: false)