Swift字符串大小写转换

uppercaseString 将字符串转成大写

lowercaseString 将字符串转成小写

capitalizedString 将字符串的首字母转成大写

let str01 = "Hi,how are you?"

let upperStr = str01.uppercaseString
// upperStr值为 "HI,HOW ARE YOU?"

let lowerStr = str01.lowercaseString
// lowerStr值为 "hi,how are you?"

let capitalStr = str01.capitalizedString
// capitalStr值为 "Hi,How Are You?"