Map a delimited string to a repeating element

Summary

Map a delimited string to a repeating element

Content

I have delimited string of ids. Example : id1,id2,id3,id4,

How can I map this string to a repeating element which is an array of ids.

That is the above string should get converted to an array with id1 id2 id3 and id4 as each of its elements.

I tried a while loop which loops till the string is "" and inside I used substring-after and substring-before to extract each of the ids.

But in this case the mapping always happen to the first element of the repeating element. i.e only id4 gets mapped.