Swift “UDP Read” 代码 - unsaferawbufferpointer 编译错误

Question

我相信有人可以在几秒钟内解决这个问题，但我对 swift 还很陌生，在 iPad 上使用 playgrounds。我正在尝试修改一些 SendUDP 代码以改为接收，但我无法解决 readResult= 行上的编译错误(unsafepointer is not convertible to unsaferawbufferpointer)。 SEND 使用非常相似的代码工作正常，但我真的在这里挣扎，超出了我的理解范围......

代码如下

func readUDP() {
  guard
  let addresses =
    try ? addressesFor(host: "192.168.4.1", port: 80)
  else {
    print("host not found")
    return
  }
  if addresses.count != 1 {
    print("host ambiguous; using the first one")
  }
  address = addresses[0]
  fd1 = socket(Int32(address.ss_family), SOCK_DGRAM, 0)
  guard fd1 >= 0
  else {
    print("`socket` failed`")
    return
  }
  defer {
    let junk = close(fd1)
    assert(junk == 0)
  }

  var message = [UInt8](repeating: 0, count: 1024)
  let messageCount = message.count
  var readResult = message.withUnsafeBytes {
    (messagePtr: UnsafePointer < UInt8 > ) - > Int in
      return address.withSockAddr {
        (sa, saLen) - > Int in
          return recvfrom(fd1, messagePtr, messageCount, 0, sa, & saLen)
      }
  }
  guard readResult >= 0
  else {
    print("read failed")
    return
  }
  print("success")
}

Answer 1

您可以使用 Swift 的 implicit bridging简化成这样:

var message = [UInt8](repeating: 0, count: 1024)
  let messageCount = message.count
  var readResult = address.withSockAddr {
    (sa, saLen) - > Int in
      return recvfrom(fd1, &message, messageCount, 0, sa, &saLen)
  }
  guard readResult >= 0
  else {
    print("read failed")
    return
  }