How to? chunk or split ?

[Isa01]

Hello,

I have to work with this kind of string

dim my string = "20130612"

I would like to get 2013-06-12. (with a - as separator every 2 characters)

I can use mid(...) or substring(...), in my case
but I would like to know if there is a existing native function in vb for that.
In php, I use chunk_split(mystring, chunkLengh)

Isa