You may use this method to fetch the device token on iOS 13 onwards:
Objective-C:
+ (NSString *)stringFromDeviceToken:(NSData *)deviceToken {
NSUInteger length = deviceToken.length;
if (length == 0) {
return nil;
}
const unsigned char *buffer = deviceToken.bytes;
NSMutableString *hexString = [NSMutableString stringWithCapacity:(length * 2)];
for (int i = 0; i < length; ++i) {
[hexString appendFormat:@"%02x", buffer[i]];
}
return [hexString copy];
}
Swift 5.0 (Untested)
class func string(fromDeviceToken deviceToken: Data?) -> String? {
let length = deviceToken?.count ?? 0
if length == 0 {
return nil
}
let buffer = UInt8(deviceToken?.bytes ?? 0)
var hexString = String(repeating: "\0", count: length * 2)
for i in 0..<length {
hexString += String(format: "%02x", buffer[i])
}
return hexString
}
Taken from OneSignal blog