How to use the UnsafeMutablePointer<UInt>? in Swift 3? : if let fileObject = NSString(contentsOfFile: strBundle, usedEncoding:Int32?

Every time that I try to work this out, I get more frustrated! Please help me! I am not sure what I need to fill in the "usedEncoding:" parameter.

Here is the error it gives me.

Cannot convert value of type 'Int32?.Type' (aka 'Optional<Int32>.Type') to expected argument type 'UnsafeMutablePointer<UInt>?'