Swift有内置的isWord函数吗？

import Foundation

func isWord(_ string: String) -> Bool {
    let pattern = "^[a-zA-Z]+$"
    let regex = try! NSRegularExpression(pattern: pattern)
    let range = NSRange(location: 0, length: string.utf16.count)
    let matches = regex.matches(in: string, range: range)
    return matches.count > 0
}

func isWordUsingSplit(_ string: String) -> Bool {
    let words = string.split { !("a"..."z").contains($0.lowercased()) }
    return words.count == 1
}

// 示例用法
let word = "Swift"
let nonWord = "Swift123"

print(isWord(word)) // 输出 true
print(isWord(nonWord)) // 输出 false

print(isWordUsingSplit(word)) // 输出 true
print(isWordUsingSplit(nonWord)) // 输出 false