ESP8266 SmartConfig

Arduino Code

you can simply call beginSmartConfig() like this

WiFi.beginSmartConfig();
while(1){
delay(1000);
if(WiFi.smartConfigDone()){
Serial.println("SmartConfig Success");
break;
}
}

or the easier way is use library that support smartConfig function such as
WiFiConnector Arduino Library: https://github.com/cmmakerclub/WiFiConnector