Question

我是Swift的新手，并尝试制作一些可以替代其他随机单词的单词。（如果你有任何进一步的建议，让它更好地工作，拜托！我很满意。）

我尝试在ViewController之后调用UITextView对象中的文本，一切都很好。当我构建并按下我的按钮时，我得到以下错误：

致命错误：在解包可选值时意外发现nil

我在这里做错了什么？

import UIKit

class ViewController: UIViewController {


    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        maintext.text = "The Dog Chases the Ball"
        self.submit.setTitle("Change It", forState: UIControlState.Normal)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    @IBOutlet var maintext: UITextView!

    @IBOutlet var submit: UIButton!
    @IBAction func submitTapped(sender: UIButton) {
        self.submit.setTitle("Again", forState: UIControlState.Normal)
        wordSwapper()

    }

}
var maintext: UITextView!
var AllWords : String! = maintext.text!
// Word Replacer Engine
extension Array {
    func randomItem() -> T {
        let index = Int(arc4random_uniform(UInt32(self.count)))
        return self[index]
    }
}

extension String {
    func replace(target: String, withString: String) -> String
    {
        return self.stringByReplacingOccurrencesOfString(target, withString: withString, options: NSStringCompareOptions.LiteralSearch, range: nil)
    }
}



// Text imported from Text Box

//: Old Text Loaded as an array

class wordSwapper {
    var Dog = ["Pup", "Canine", "Wolf"]
    var Ball = ["Frisbee", "Stick", "Car"]

        init(){
            var WordsArray = AllWords.componentsSeparatedByString(" ")



            //: New Word Library



    AllWords.replace("Dog", withString: Dog.randomItem()).replace("Ball", withString: Ball.randomItem())



    for Dog in WordsArray {
    AllWords.replace("Dog", withString: "Pup")
    }

    for Ball in WordsArray {
    AllWords.replace("Ball", withString: "Frisbee")
    }

    }

}

Answer 1

您在此处覆盖您的IBOutlet：

var maintext: UITextView!

这就是你的方法wordSwapper（）中为零的原因。

Answer 2

我仍然掌握着swift，并意识到我正在从两个不同的类中调用一个变量。 maintext类是视图控制器的变量，所以我不得不在我首先创建的新类中调用视图控制器。

解包时发现UITextView为零的原因

2 个答案: