SpecialCacluator.swift

import UIKit

class ViewController: UIViewController {
  
  var displayedFigure : Double = 0
  var previousFigure : Double = 0
  var operatorInView = false
  var operation = 0
  
  @IBOutlet var displayLabel: UILabel!
  override func viewDidLoad() {
    super.viewDidLoad()
  }
  
  
  @IBAction func happened(_ sender: UIButton) {
    
    if operatorInView {
      
      displayLabel.text = String(sender.tag - 1)
      displayedFigure = Double(displayLabel.text!)!
      operatorInView = false
      
    } else {
      displayLabel.text = displayLabel.text! + String(sender.tag - 1)
      displayedFigure = Double(displayLabel.text!)!
      
    }
  }
  
  
  @IBAction func Operators(_ sender: UIButton) {
    
    
    if displayLabel.text != "" && sender.tag != 11 && sender.tag != 16 {
      
      
      previousFigure = Double(displayLabel.text!)!
      
      switch sender.tag {
      case 12: displayLabel.text = "/"
      case 13: displayLabel.text = "*"
      case 14: displayLabel.text = "-"
      case 15: displayLabel.text = "+"
        
        
      default : break
      }
      operation = sender.tag
      operatorInView = true
      
      
      //MARK:- User Clicks '='
    } else if sender.tag == 16 {
      
      
      switch operation {
      case 12: displayLabel.text = String(previousFigure / displayedFigure)
      case 13: displayLabel.text = String(previousFigure * displayedFigure)
      case 14: displayLabel.text = String(previousFigure - displayedFigure)
      case 15: displayLabel.text = String(previousFigure + displayedFigure)
        
      default:
        break
      }
      
      
      
      
  //MARK:- User Clicks 'C'
    } else if sender.tag == 11 {
      
      
      operatorInView = false
      displayLabel.text = ""
      displayedFigure = 0
      previousFigure = 0
      operation = 0
      
      
      
    }
    
  }
  
  
  
}

Hey,
Thanks for the code but i seem to get an error for - line 27 - displayedFigure = Double(displayLabel.text!)!
Thread 1: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)

Can you let me know how to remove the error