Question frame (How long have you been living in chicago?)

[pavanhotscan]

my friend is staying in chicago , i know that .

then i asked him " how long have you been living in chicago ?"

or

" how long have you been in chicago "

which one is correct ?

can you give me an explanation for the above question ?

[Mister Micawber]

.
Both are fine.
.
_________________
Canadian-American native speaker
who teaches English for a living at Mister Micawber's
ESL cafe: Interview with Mister Micawber