Samsung announced this during CES but how likely is this? Anytime soon? I just ordered one for my fiance without knowing it's not compatible with her iphone (stupid me), and will probably just return it when I receive it in a few days.
Samsung has been steadily dribbling out improvements for the Gear S2, and they did project that the iPhone app would come in March, so it's too soon to think they've given up on the idea. But they have been consistently behind schedule with many of their software promises (e.g., Samsung Pay compatibility). So I wouldn't buy a Gear S2 now in the expectation that the iPhone app will appear any day. (Verizon announced, but then withdrew, a claim that their latest Gear S2 update would include iPhone compatibility: Samsung Gear S2 iOS support lands on Verizon - SlashGear)