swift sort characters in a string

问题

How to sort characters in a string e.g. "5121" -> "1125" ?

I can do this with code below but it seems too slow:

var nonSortedString = "5121"
var sortedString = String(Array(nonSortedString.characters).sort())

回答1:

The CharacterView handles properly compound characters and provides proper ordering ("eěf" vs. "efě"). If you are ok with the way C++ handles unicode characters, try using one of the other views, like nonSortedString.utf16.sort(). It should give speed similar to C++.

来源：https://stackoverflow.com/questions/31904356/swift-sort-characters-in-a-string