.characters deprecated? From Listing 7.4

Latest XCODE marks the .characters as deprecated, from Listing 7.4. Could use some help understanding how the implementation should work in XCODE 8.4.1. Thanks.

Going to the on line reference manual at swift.org I found that

for c: Character in mutablePlayground {


characters’ is deprecated: Please use String or Substring directly

and my print The results of :
print(“aAcute:(aAcute.characters.count); aAcutePrecomposed :(aAcutePrecomposed.characters.count)”);//aAcute:1;AacutePrecomposed :2
maybe my computer broken…
What should I do