swift实现简易计算器项目

import UIKit

class ViewController: UIViewController {
    @IBOutlet weak var result: UILabel!


    var n1: String = ""
    var n2: String = ""
    var n3: String = ""

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

    }


    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()

        // Dispose of any resources that can be recreated.

    }


    @IBAction func didClick(sender: UIButton) {
        let temp = sender.currentTitle

        if temp == "AC" {
            n1 = ""
            n2 = ""

          result.text = "0"
            return

        }

        else if temp == "+" || temp == "-" || temp == "*" || temp == "/" {
          n1 = result.text!
          n2 = ""
          n3 = temp!

          return

        }

        else if temp == "=" {
            var result1: Double = 0
               println("n1:"+n1+" n2:"+n2)

            switch n3 {
             case "+":
                result1 = (n1 as NSString).doubleValue + (n2 as NSString).doubleValue          
             case "-":
                result1 = (n1 as NSString).doubleValue - (n2 as NSString).doubleValue
 
             case "*":
                result1 = (n1 as NSString).doubleValue * (n2 as NSString).doubleValue
             case "/":
                result1 = (n1 as NSString).doubleValue / (n2 as NSString).doubleValue
             default:
                result1 = 0

            }

            result.text = "\(result1)"
            n3 = ""
            return            

        }
        
        if n3 != "" {
          n2 = n2 + temp!

          result.text = n2

        }else {
          n1 = n1 + temp!

          result.text = n1


        }


    }


}