How to convert String to UnsafePointer and length

Question

When I using NSOutputStream\'s write method

func write(_ buffer: UnsafePointer, maxLength length: Int) -> Int
         


        

Answer 1

Here is how to do it in Swift 3. Run fine in Swift 4 too

extension String {

  func toPointer() -> UnsafePointer? {
    guard let data = self.data(using: String.Encoding.utf8) else { return nil }

    let buffer = UnsafeMutablePointer.allocate(capacity: data.count)
    let stream = OutputStream(toBuffer: buffer, capacity: data.count)

    stream.open()
    data.withUnsafeBytes({ (p: UnsafePointer) -> Void in
      stream.write(p, maxLength: data.count)
    })

    stream.close()

    return UnsafePointer(buffer)
  }
}

To convert from String to UnsafeMutablePointer

let cString = strdup("Hello") // UnsafeMutablePointer

To convert from UnsafeMutablePointer to String

let string = String(cString: cString!) // String