Can boron and iodine form an ionic bond

Not likely. The electronegativity difference between boron (2.0) and I (2.6) is only 0.6. In ionic bonds, this difference is usually 1.8 or greater. So B and I are much more likely to form a covalent bond.

There is no point on the electronegativity difference continuum where a "covalent bond" suddenly turns into an "ionic bond." I've seen ΔEN values of 1.67, 1.7, and now 1.8 as the "magic number." The bottom line is that "ionic" and "covalent" are "ideal bonds", but the bonds in actual chemical compounds are "real bonds" and therefore have some characteristics of both. In the case of boron and iodine, the bond is much more covalent in nature, with an electronegativity difference of 0.62 which gives us a percent ionic character slightly less than 10%. Or we can say that the bond has about 90% covalent character.

Compound bond: Two different elements bonded.
Ionic bond: An ionic bond is a type of chemical bond formed through an electrostatic attraction between two oppositely charged ions.

So, yes.