#include <ESP32Servo.h>
Servo myservo;
int pos = 0;

#define relay 0

#define sw1 4
int val = 0;

void setup() 
{
  pinMode(relay, OUTPUT);
  myservo.attach(2);
  pinMode(sw1, INPUT_PULLUP);
}

void loop()
{ 
  val = digitalRead(sw1);
  if (val==LOW)
  {
    digitalWrite(relay, HIGH);
    for (pos = 0; pos <= 180; pos += 1) 
    { 
      myservo.write(pos);              
      delay(5);                       
    }
    for (pos = 180; pos >= 0; pos -= 1) 
    { 
      myservo.write(pos);              
      delay(5);                       
    }
  }
  else
  {
    digitalWrite(relay, LOW);
  }
}