Question

我试图根据布尔变量的值在viewController中加载两个不同的字符串数组之一。布尔值需要由可以从2个viewController调用的segue传递，其中一个将boolean设置为false，而另一个设置为true。

我试过将prepareForSegue（segue :)方法与performSegue（withIdentifier :)结合使用。设置了所有情节提要剧情链接和标识符。我还尝试将目标viewController嵌入到navigationController中，并调整segue代码以引用navigationController。

import UIKit

class homeworkViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {

    var useHomework = Bool()
    var homeworkWords = [String]()

    override func viewDidLoad() {
        super.viewDidLoad()

        loadHomeworkWords()

        navigationItem.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: .play, target: self, action: #selector(test))
    }

    func loadHomeworkWords() {
        if let defaults = UserDefaults(suiteName: "group.co.uk.tirnaelectronics.hyperpolyglot.todayview") {
            if var savedHomeWorkWords = defaults.object(forKey: "homeworkWords") as? [String] {
                print("savedLanguages array is: \(savedHomeWorkWords)")
                homeworkWords.removeAll()
                homeworkWords = savedHomeWorkWords
                savedHomeWorkWords.removeAll()
                print("savedHomeWorkWords after removeAll: \(savedHomeWorkWords)")
                print("loadHomeworkWords homeworkWords are: \(homeworkWords)")
            }
        }
    }

    func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        if segue.identifier == "Test" {
            if let testVC = segue.destination as? TestViewController {
                testVC.useHomework = useHomework
            }
        }
    }

    @objc func test() {
        if homeworkWords.isEmpty == true {
            let ac = UIAlertController(title: "Add some homework!", message: nil, preferredStyle: .alert)
            let okAction = UIAlertAction(title: "OK", style: .default)
            ac.addAction(okAction)
            present(ac, animated: true)
        } else {
            useHomework = true
            self.performSegue(withIdentifier: "Test", sender: self)
        }
    }
}

import UIKit

class TestViewController: UIViewController, UITextFieldDelegate {

    var words: [String]!
    var useHomework = Bool()
    var homeworkWords = [String]()
    var chosenLanguage = String()
    let wordsString = "Words"

    override func viewDidLoad() {
        super.viewDidLoad()

        print("useHomework is: \(useHomework)")

        if useHomework == false {
            loadWords(fromWordsArray: "words")
        } else {
            loadWords(fromWordsArray: "homeworkWords")
        }

        print("words just before shuffle: \(words!)")
        words.shuffle()
        print("words just after shuffle: \(words!)")
    }

    func loadWords(fromWordsArray: String) {
        if let defaults = UserDefaults(suiteName: "group.co.uk.tirnaelectronics.hyperpolyglot.todayview") {
            if fromWordsArray == "words" {
                if var savedWords = defaults.object(forKey: "\(chosenLanguage)\(wordsString)") as? [String] {
                    print("chosen words in loadWords in TestViewcontroller are: \(savedWords)")
                    words = savedWords
                    savedWords.removeAll()

                }
            } else {
                if var savedWords = defaults.object(forKey: "homeworkWords") as? [String] {
                    print("savedWords array is: \(savedWords)")
                    words = savedWords
                    savedWords.removeAll()
                    print("homeworkWords in loadWords in TestViewcontroller are: \(savedWords)")
                }
            }
        }
    }
}

从任一类中选择时，调试控制台始终将useHomework报告为false。当我在testViewController的类初始化程序中将useHomework设置为true时，我得到了预期的结果。

homeworkWords数组包含正确的字符串值，这些字符串值已添加到homeworkWords中，并保存到与testViewController相连的其他（单词）viewController中的userDefaults中。

homeworkWords永远不会加载并保存到单词字符串数组，因为在布尔条件测试中永远不会调用loadWords（fromWordsArray：）。

Answer 1

在TestViewController中，从

更改useHomework的声明。

var useHomework = Bool()

遵循以下条件：

var useHomework: Bool?

并通过在使用位置展开“ useHomework”对其进行适当的更改。

通过情节提要segue在类之间传递时，布尔变量始终为false

1 个答案: