Swift 跳过“else if”答案

【问题标题】：Swift skips an "else if"Swift 跳过“else if”
【发布时间】：2019-03-01 17:58:43
【问题描述】：

这个 Swift (Xcode) ChatBot 程序正确返回“你好”和“cookie 在哪里？”字符串。但是对于应该是“向北！”的中间两个返回“可能是任何东西”。我认为这是一个断点或多行字符串的问题，但这发生在 Xcode 工作场所和游乐场：

struct MyQuestionAnswerer {
    func responseTo(question: String) -> String {

        let question = question.lowercased()

        let defaultNumber = question.count % 3

        if question == "hello there" {
            return "Why hello there"
        } else if question == "where should I go on holiday?" {
            return "To the North!"
        } else if question == "where can I find the north pole?" {
            return "To the North!"
        } else if question == "where are the cookies?" {
            return "In the cookie jar!"
        } else if defaultNumber == 0 {
            return "That really depends"
        } else if defaultNumber == 1 {
            return "Ask me again tomorrow"
        } else {
            return "Could be anything"
        }
    }
}

【问题讨论】：

标签： swift string if-statement return

【解决方案1】：

请阅读我在代码块中添加的 cmets

struct MyQuestionAnswerer {
func responseTo(question: String) -> String {

    let question = question.lowercased()  // <- Converts all the strings in your question into lower case

    let defaultNumber = question.count % 3

    if question == "hello there" {
        return "Why hello there"
    } else if question == "where should I go on holiday?" {  // <- I is upper case
        return "To the North!"
    } else if question == "where can I find the north pole?" {  // <- I is upper case
        return "To the North!"
    } else if question == "where are the cookies?" {
        return "In the cookie jar!"
    } else if defaultNumber == 0 {
        return "That really depends"
    } else if defaultNumber == 1 {
        return "Ask me again tomorrow"
    } else {
        return "Could be anything"
    }
}

}

所以本质上，您是在比较“i...应该在哪里”与“我应该在哪里>..."，由于这个比较是假的，并且它不匹配任何其他 if 块，它会落到最后一个 else 块。

【讨论】：

谢谢！唷，我需要一些新鲜的眼睛来捕捉它。

【解决方案2】：

您的问题是使用 .lowercased() - 比较两个字符串 being.lowercased 如果你使用 case 语句，这个问题对我来说看起来更好：见下文

struct MyQuestionAnswerer {
    func responseTo(question: String) -> String {

        let localQuestion = question.lowercased()
        question == String("where can I find the north pole?").lowercased()
        let defaultNumber = question.count % 3

        switch localQuestion {
        case String("hello there").lowercased() : return "Why hello there"
        case String("where should I go on holiday?").lowercased() : return "To the North!"
        case String("where can I find the north pole?").lowercased() : return "To the North!"
        case String("where are the cookies?").lowercased() : return "In the cookie jar!"
        default: if (defaultNumber == 0) {return "That really depends" } else {return "Could be anything"}
        }
    }
}

【讨论】：

感谢您的建议！