Swift 2.0(单行):

String(nameOfString.characters.prefix(1)).uppercaseString + String(nameOfString.characters.dropFirst())

全部小写。小写()

首字母大写，其他字母小写，大写

全部大写。uppercase ()

Swift 3更新

replaceRange函数现在是replaceSubrange

nameOfString.replaceSubrange(nameOfString.startIndex...nameOfString.startIndex, with: String(nameOfString[nameOfString.startIndex]).capitalized)

在Swift 3.0中(这比公认的答案更快更安全):

extension String {
    func firstCharacterUpperCase() -> String {
        if let firstCharacter = characters.first {
            return replacingCharacters(in: startIndex..<index(after: startIndex), with: String(firstCharacter).uppercased())
        }
        return ""
    }
}

nameOfString。大写是不行的，句子里的每个单词都要大写

我的解决方案:

func firstCharacterUppercaseString(string: String) -> String {
    var str = string as NSString
    let firstUppercaseCharacter = str.substringToIndex(1).uppercaseString
    let firstUppercaseCharacterString = str.stringByReplacingCharactersInRange(NSMakeRange(0, 1), withString: firstUppercaseCharacter)
    return firstUppercaseCharacterString
}

字符串中的第一个字符大写

extension String {
    var capitalizeFirst: String {
        if self.characters.count == 0 {
            return self

        return String(self[self.startIndex]).capitalized + String(self.characters.dropFirst())
    }
}