Get device token for push notification

NOTE: The below solution no longer works on iOS 13+ devices - it will return garbage data.

Please use following code instead:

+ (NSString *)hexadecimalStringFromData:(NSData *)data
{
  NSUInteger dataLength = data.length;
  if (dataLength == 0) {
    return nil;
  }

  const unsigned char *dataBuffer = (const unsigned char *)data.bytes;
  NSMutableString *hexString  = [NSMutableString stringWithCapacity:(dataLength * 2)];
  for (int i = 0; i < dataLength; ++i) {
    [hexString appendFormat:@"%02x", dataBuffer[i]];
  }
  return [hexString copy];
}

Solution that worked prior to iOS 13:

Objective-C

- (void)application:(UIApplication *)app didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken 
{
    NSString *token = [[deviceToken description] stringByTrimmingCharactersInSet: [NSCharacterSet characterSetWithCharactersInString:@"<>"]];
    token = [token stringByReplacingOccurrencesOfString:@" " withString:@""];
    NSLog(@"this will return '32 bytes' in iOS 13+ rather than the token", token);
} 

Swift 3.0

func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data)
{
    let tokenString = deviceToken.reduce("", {$0 + String(format: "%02X", $1)})
    print("this will return '32 bytes' in iOS 13+ rather than the token \(tokenString)")
}