import Foundation
import SystemConfiguration

var reach:SCNetworkReachability!

reach = SCNetworkReachabilityCreateWithName(kCFAllocatorDefault, "apple.com").takeRetainedValue()

typealias ChangeBlock = (UInt32) -> ()

let block:ChangeBlock = {status in
    // swift compleation block
}

let blockPtr = UnsafeMutablePointer<ChangeBlock>.alloc(1)
blockPtr.initialize(block)
let blockVoidPtr = UnsafeMutablePointer<Void>(blockPtr)

// Create callback
let callback:(SCNetworkReachability!, SCNetworkReachabilityFlags, UnsafeMutablePointer<Void>) -> () = { (target, flags, info) in
    let ptr = UnsafeMutablePointer<ChangeBlock>(info)
    let block:ChangeBlock = ptr.memory
    
    block(flags)
}

// Create UnsafeMutablePointer and initialise with callback
let callbackPtr = UnsafeMutablePointer<(SCNetworkReachability!, SCNetworkReachabilityFlags, UnsafeMutablePointer<Void>) -> Void>.alloc(1)
callbackPtr.initialize(callback)

// convert UnsafeMutablePointer to COpaquePointer
let cop = COpaquePointer(callbackPtr)

// convert COppaquePointer to CFunctionPointer
let cfptr = CFunctionPointer<(SCNetworkReachability!, SCNetworkReachabilityFlags, UnsafeMutablePointer<Void>) -> Void>(cop)

let context = SCNetworkReachabilityContext(version: 0, info: blockVoidPtr, retain: nil, release: nil, copyDescription: nil)
let contextPtr = UnsafeMutablePointer<SCNetworkReachabilityContext>.alloc(1)
contextPtr.initialize(context)

SCNetworkReachabilitySetCallback(reach, cfptr, contextPtr)


let que = dispatch_queue_create("me.swiftti.reachability", nil)

SCNetworkReachabilitySetDispatchQueue(reach, que)


// on deinit() do
contextPtr.destroy()
contextPtr.dealloc(1)
callbackPtr.destroy()
callbackPtr.dealloc(1)
blockVoidPtr.destroy()
blockVoidPtr.dealloc(1)