致命错误：在展开可选值计算时意外发现nil(fatal error: unexpectedly found nil while unwrapping an Optional value Computa

致命错误：在展开可选值计算时意外发现nil(fatal error: unexpectedly found nil while unwrapping an Optional value Computation) import UIKit class ViewController: UIViewController { @IBOutlet weak var yourScore: UITextField! @IBOutlet weak var totalScore: UITextField! @IBOutlet weak var labelText: UILabel! @IBAction func buttonPressed(sender: AnyObject) { let score1: Int = yourScore.text.toInt()! let score2: Int = totalScore.text.toInt()! let mistakes = score2 - score1 let scoreFinal = ((((score2 / 2) - mistakes)*23)/score2)+75 labelText.text = "\(scoreFinal)" } 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. } }

我的代码有问题。 是因为数据类型还是什么？ 当我加载应用程序时，它只是打开正常，但按下按钮时，应用程序崩溃。

http://i.stack.imgur.com/B2i5Z.png

import UIKit class ViewController: UIViewController { @IBOutlet weak var yourScore: UITextField! @IBOutlet weak var totalScore: UITextField! @IBOutlet weak var labelText: UILabel! @IBAction func buttonPressed(sender: AnyObject) { let score1: Int = yourScore.text.toInt()! let score2: Int = totalScore.text.toInt()! let mistakes = score2 - score1 let scoreFinal = ((((score2 / 2) - mistakes)*23)/score2)+75 labelText.text = "\(scoreFinal)" } 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. } }

Something is wrong with my code. Is it because of data types or something? When I load the application, it just opens fine but when the button is pressed, the app crashes.

http://i.stack.imgur.com/B2i5Z.png

最满意答案

if let你可以安全地解包值：

if let score1 = yourScore.text.toInt() { if let score2 = totalScore.text.toInt() { let mistakes = score2 - score1 let scoreFinal = ((((score2 / 2) - mistakes)*23)/score2)+75 labelText.text = "\(scoreFinal)" } else { // no valid score2 } } else { // no valid score1 }

You could safely unwrap the values with if let:

if let score1 = yourScore.text.toInt() { if let score2 = totalScore.text.toInt() { let mistakes = score2 - score1 let scoreFinal = ((((score2 / 2) - mistakes)*23)/score2)+75 labelText.text = "\(scoreFinal)" } else { // no valid score2 } } else { // no valid score1 }