如果您使用的是swift 2：
就改这一行

for character in string {

至

for character in string.characters {

而且它会工作得很好

count("hello") // (.0 2, .1 3)

这里的问题是你为你的方法选择的名字。尝试count以外的任何名字，你应该没问题。
编辑/更新：雨燕4
第一个
如果您只想计算每个单词的第一个字母，则需要将字符串分解为单词数组，并提取每个第一个字母的小写字母，如下所示：
第一个
请注意，扩展名应放置在项目内的新Swift文件中。

另一个选项是使用正则表达式来检索每个单词的第一个字母。\b选项用于查找单词边界，而\w是一个单词字符。因此，一旦您转义反斜杠，\\b\\w将捕获紧跟在单词边界后面的第一个字母（也就是每个单词的第一个字母）：

func countLetters(string: String) -> (vowels: Int, consonants: Int) {
    var vowels = 0, consonants = 0
    let regex = NSRegularExpression(pattern: "\\b\\w", options: nil, error: nil)
    regex?.enumerateMatchesInString(string, options: nil, range: NSMakeRange(0, count(string))) { matches, flags, stop in
        switch (string as NSString).substringWithRange(matches.range).lowercaseString {
        case "a","e","i","o","u":
            ++vowels
        case "b","c","d","f","g","h","j","k","l","m","n","p","q","r","s","t","v","w","x","y","z":
            ++consonants
        default: break
        }
    }
    return (vowels, consonants)
}

--
如果您想要处理重音字符（例如“étude”），您可能需要先移除这些音调符号：

func countLetters(string: String) -> (vowels: Int, consonants: Int) {
    let convertedString = NSMutableString(string: string)
    CFStringTransform(convertedString, nil, kCFStringTransformStripCombiningMarks, Boolean(0))

    var vowels = 0, consonants = 0
    let regex = NSRegularExpression(pattern: "\\b\\w", options: nil, error: nil)
    regex?.enumerateMatchesInString(convertedString as String, options: nil, range: NSMakeRange(0, convertedString.length)) { matches, flags, stop in
        switch convertedString.substringWithRange(matches.range).lowercaseString {
        case "a","e","i","o","u":
            ++vowels
        case "b","c","d","f","g","h","j","k","l","m","n","p","q","r","s","t","v","w","x","y","z":
            ++consonants
        default: break
        }
    }
    return (vowels, consonants)
}