iOS作業四-小費計算

//
//  ViewController.swift
//  Tipcalcultion
//
//  Created by Feng on 2016/10/25.
//  Copyright © 2016年 Fang. All rights reserved.
//

import UIKit

class ViewController: UIViewController {

    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.
    }
    @IBOutlet weak var cost: UITextField!
    
    @IBOutlet weak var tip: UITextField!

    @IBOutlet weak var result: UILabel!
    
    @IBAction func compute(_ sender: AnyObject) {
        if(cost.text == "" || tip.text == ""){
            result.text = "請輸入金額!" //防呆使用
        } else {
            let thecost = Double(cost.text!) //原始金額
            let thetip = Double(tip.text!)!/100 //除以百分比
            result.text = String((thecost! * thetip)+thecost!) // (金額*小費) + 金額 = 最終金額
        }
        
    }
    
    

}