使用Swift提取字符串中的最后一个单词 [英] Extract Last Word in String with Swift

问题描述

在Swift中提取String中的最后一个单词的方法是什么？因此，如果我有Lorem ipsum dolor sit amet，请返回amet。这样做的最有效方法是什么？

What is the way of extracting last word in a String in Swift? So if I have "Lorem ipsum dolor sit amet", return "amet". What is the most efficient way of doing this?

推荐答案

您可以使用String方法enumerateSubstringsInRange。第一个参数只传递你的String characters.indices和选项.ByWords。只需将每个子字符串附加到最终数组并返回它。

You can use String method enumerateSubstringsInRange. First parameter just pass your String characters.indices, and the option .ByWords. Just append each substring to the final array and return it.

Xcode 8.1•Swift 3.0.1或更高版本

extension String {
    var byWords: [String] {
        var byWords:[String] = []
        enumerateSubstrings(in: startIndex..<endIndex, options: .byWords) {
            guard let word = $0 else { return }
            print($1,$2,$3)
            byWords.append(word)
        }
        return byWords
    }
    func firstWords(_ max: Int) -> [String] {
        return Array(byWords.prefix(max))
    }
    var firstWord: String {
        return byWords.first ?? ""
    }
    func lastWords(_ max: Int) -> [String] {
        return Array(byWords.suffix(max))
    }
    var lastWord: String {
        return byWords.last ?? ""
    }
}

---

用法：

---

Usage:

let sentence = "Out of this world!!!"
let firstWord = sentence.firstWord       // "Out"
let lastWord = sentence.lastWord         // world"
let words = sentence.byWords             // ["Out", "of", "this", "world"]
let first2Words = sentence.firstWords(2) // ["Out", "of"]
let last2Words = sentence.lastWords(2)   // ["this", "world"]

---

Swift 2

extension String {
    var byWords: [String] {
        var result:[String] = []
        enumerateSubstringsInRange(characters.indices, options: .ByWords) {
            guard let substring = $0.substring else { return }
            result.append(substring)
        }
        return result
    }
}

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