The title and layman interpretations is wrong. Being dominant is not illegal. Being a monopoly is not illegal. Abusing dominance or abusing a monopoly position is illegal.
That and the fact that Apple isn't actually dominant (depending on how far you want to split down the definition of "phone" or "smart phone" or "high end smart phone" or "very high end smart phone".
Even if Apple is dominant, there's no law on this planet that says "you can't make your products from parts you make".