dear aswin , the main thng which should be kept in mind is that the compound should have 3 alfa acidic hydrogens(presence of methyl group) ...
this is the only condition ...
example => acetone, acetophenone , acetaldehyde , ....
case1) if there are only two alfa hydoogens & Iodo group present at alfa pos then this will give iodoform rxn...
case 2) if there are only 1 alfa hydorgen & 2 Iodo groups then also this will give this test
case3) if there are no acidic hydrogens but 3 Iodo groups present then also this will give Iodoform test ...
there is no particular change for aeromatic or aliphatic , the need is three acidic hydorgens only....