Designing a System that would detect typos and suggestions

Question

This was asked in an interview.

I think the answer can be done by constructing a trie of all valid words and then suggestions can be made based on a possible valid path which was otherwise given as incorrect.

Say if user types apfle, and system would detect that after ap a possible valid path was app, which would then satisfy apple.

Is there any better solution than this? Perhaps the one implemented by spell checkers.