toLowerCase
Create lower case transformed OudsAnnotatedString.
The lowercase sometimes maps different number of characters. This function adjusts the text style and paragraph style ranges to transformed offset.
Note, if the style's offset is middle of the lowercase mapping context, this function won't transform the character, e.g. style starts from between base alphabet character and accent character.
Return
A lowercase transformed string.
Parameters
localeList
A locale list used for lower case mapping. Only the first locale is effective. If empty locale list is passed, use the current locale instead.