Swift获取汉字的首字母

//获取拼音首字母（大写字母）
func findFirstLetterFromString(aString: String) -> String {
    //转变成可变字符串
    let mutableString = NSMutableString.init(string: aString)

    //将中文转换成带声调的拼音
    CFStringTransform(mutableString as CFMutableString, nil,      kCFStringTransformToLatin, false)

    //去掉声调
    let pinyinString = mutableString.folding(options:          String.CompareOptions.diacriticInsensitive, locale:   NSLocale.current)

    //将拼音首字母换成大写
    let strPinYin = polyphoneStringHandle(nameString: aString,    pinyinString: pinyinString).uppercased()

    //截取大写首字母
    let firstString = strPinYin.substring(to:     strPinYin.index(strPinYin.startIndex, offsetBy: 1))

    //判断首字母是否为大写
    let regexA = "^[A-Z]$"
    let predA = NSPredicate.init(format: "SELF MATCHES %@", regexA)
    return predA.evaluate(with: firstString) ? firstString : "#"
}

//多音字处理，根据需要添自行加
func polyphoneStringHandle(nameString: String, pinyinString: String) -> String {
    if nameString.hasPrefix("长") {return "chang"}
    if nameString.hasPrefix("沈") {return "shen"}
    if nameString.hasPrefix("厦") {return "xia"}
    if nameString.hasPrefix("地") {return "di"}
    if nameString.hasPrefix("重") {return "chong"}
    return pinyinString
}