Trouble converting device token Swift 3

Question

I am trying to convert a device token and using the following code (swift 3):

parameters["device_token"] = request.deviceToken.reduce("", {$0 + String(format: "%02X", $1)}).

However I am getting the compiler error Binary operator '+' cannot be applied to operands of type Any? and String. What am I doing wrong here?

Anbu.Karthik · Accepted Answer · 2016-10-04T04:07:28.857

6

try this

func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {

var token = ""

for i in 0..<deviceToken.count {
 token = token + String(format: "%02.2hhx", arguments: [deviceToken[i]])
  }

  print("Registration succeeded!")
  print("Token: ", token)
 }

edited Oct 04 '16 at 04:07

answered Oct 04 '16 at 04:00

Anbu.Karthik

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`Cannot invoke initializer for type 'UnsafePointer' with an argument list of type '(UnsafeRawPointer)'`. Getting that error. – KexAri Oct 04 '16 at 04:04
Brilliant that worked. Can you tell me what `format: "%02.2hhx"` does? – KexAri Oct 04 '16 at 04:17
@KexAri - see this http://stackoverflow.com/questions/30463962/printf-char-as-hex-in-c – Anbu.Karthik Oct 04 '16 at 04:18

Martin R · Answer 2 · 2016-10-04T07:27:10.957

Actually your code using reduce to convert the device token to a hex string is correct. But apparently parameters has the type NSMutableDictionary (or [String: Any]), and the compiler tries to match the initial value "" to Any?.

As a workaround, you can assign the hex string to a temporary variable first:

let hexToken = request.deviceToken.reduce("", {$0 + String(format: "%02X", $1)})
parameters["device_token"] = hexToken

or use the trailing closure syntax instead:

parameters["device_token"] = deviceToken.reduce("") {$0 + String(format: "%02X", $1)}

Both methods make your code compile, so this could be a compiler bug.

Trouble converting device token Swift 3

2 Answers2