"We investigate the idea that women’s flaunting of designer products functions as a signaling system directed at same-sex rivals who pose a threat to a woman’s relationship. We hypothesize that some women use pricey possessions to signal to other women that their romantic partner is especially devoted to them. In turn, flaunting designer handbags and shoes helps women deter romantic rivals from poaching their relationship partner"
Today iPhones and MacBook are mostly mass market for the middle class, as you can see from their presence in universities. Out of all the women owning an iPhone, and there's a lot, I've yet to meet one whose iPhone was bought by their 'devoted romantic partner'. They either bought it themselves, or their parents bought it in the family plan. And usually the phone itself is paid monthly with the plan.
Showing an iPhone does not have the same signalling effect as wearing "luxurious designer handbags", designer shoes, and "expensive jewelry".