I am trying to upgrade the following code from swift 2 to 3 and I get withUnsafePointers is unavailable: use nesterd withUnsafePointer instead. I have tried it a couple ways but I can't get it right. He is my code

```
  var v: LinphoneManager = self
  var lct: LinphoneCoreVTable = LinphoneCoreVTable()
       let theLinphoneCore : OpaquePointer = withUnsafePointers(&lct, &v, { (ptr: UnsafePointer<LinphoneCoreVTable>, selfPtr: UnsafePointer<LinphoneManager>) -> OpaquePointer in

                let voidPtr: UnsafeMutableRawPointer = unsafeBitCast(selfPtr, to: UnsafeMutableRawPointer.self)
             return linphone_core_new_with_config (ptr, self.configDb!, voidPtr /* user_data */)
        })

```