view.swift

func commentButtonSlideIn(fromRight:Bool = true){
  
    if(fromRight){
      myButton.trailingAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.trailingAnchor, constant: 15).isActive = true
      myButton.frame.origin.x = UIScreen.main.bounds.width
    }else{
      myButton.leadingAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.leadingAnchor, constant: -15).isActive = true
      myButton.frame.origin.x = -80
    }
    
    var destX = UIScreen.main.bounds.width - (80 - 15)
    if(!fromRight){
      destX = -15
    }
    
    let layer = myButton.layer
    UIViewPropertyAnimator(duration: 0.5, curve: .easeIn, animations: {
      layer.frame.origin.x = destX
    }).startAnimation()
  }