leetcode苹果-Character-and-CharacterSet:字符集

leetcode 苹果特点 Apple 文档：Character 类型表示由一个或多个 Unicode 标量值组成的字符，按 Unicode 边界算法分组。 通常， > Character 实例匹配字符串的读者将其视为单个字符的内容。 字符串是 Character 实例的集合，因此可见字符的数量通常是计算字符串长度的最自然的方法。 isLowercase for char in " Alex " { if char. isLowercase { print ( " \( char ) is a lower letter " ) } } /* l is a lower letter e is a lower letter x is a lower letter */ isCurrencySymbol let amount = " $100 " let firstChar = amount. first ?? " " if firstChar. isCurrencySymbol { print ( " valid currency " ) } else { print ( " not a