Swift 3.0 学习 -- 大写和小写字符串(Uppercase and Lowercase Strings)

在swift2.0的时候，您可以通过字符串的uppercaseString和lowercaseString属性来访问大写/小写版本的字符串。如下：

let normal = "Could you help me, please?"let shouty = normal.uppercaseString// shouty 值为 "COULD YOU HELP ME, PLEASE?"let whispered = normal.lowercaseString// whispered 值为 "could you help me, please?"

但是在swift3.0中，字符串的uppercaseString和lowercaseString属性被函数 uppercased()和 lowercased()代替，如下：

let normal = "Could you help me, please?"let shouty = normal.uppercased()// shouty 值为 "COULD YOU HELP ME, PLEASE?"let whispered = normal.lowercased()// whispered 值为 "could you help me, please?"