Question

对于基本问题道歉，我是斯威夫特的新人，而且我已经被困在这一段时间但却找不到帮助。

我尝试在我的math应用中执行简单的addition操作，例如multiplication，division和iOS等操作但是避难所＆＃39能够。

当我尝试add两个double个数字（weightField和heightField）时，我会得到一个连结string而不是sum 。

如何在swift中执行简单的数学运算？

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var weightField: UITextField!

    @IBOutlet weak var heightField: UITextField!

    @IBAction func goButton(sender: AnyObject) {

        resultField.text = weightField.text + heightField.text
    }

    @IBOutlet weak var resultField: UILabel!

    @IBOutlet weak var commentField: UILabel!

    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.
    }


}

Answer 1

您不会将字符串的值添加到一起，因此如果您确定文本可以转换为Int，则可以执行以下操作：

// in Swift 1.x
resultField.text = String(weightField.text.toInt()! + heightField.text.toInt()!)

// and double values
let weight = (weightField.text as NSString).doubleValue
let height = (heightField.text as NSString).doubleValue
resultField.text = String(weight + height)
// but if it cannot parse the String the value is 0.0. (No optional value)


// in Swift 2
resultField.text = String(Int(weightField.text)! + Int(heightField.text)!)

// and you can even use a double initializer
resultField.text = String(Double(weightField.text)! + Double(heightField.text)!)

Answer 2

使用NSString：

resultField.text = String(stringInterpolationSegment: (weightField.text as NSString).doubleValue + (heightField.text as NSString).doubleValue)

Answer 3

基本上你是连接字符串而不是数字。您需要将字符串转换为整数，然后添加它们。

var a = weightField.text

var b =  heightField.text

var c = (a as! NSString).doubleValue +  (b as! NSString).doubleValue

resultField.text = String(format "%.2f",c)

加法运算符（+）仅在swift中执行连接而不是添加

3 个答案: