HRM w/ Iphone Integration

Hello, there, I'm sending this out to people who have HRM that have an integration with the Iphone!

I have an iphone in a LifeProof case, and I'm already on the way to having a LP arm band for using it for music (and tech-protection) while working out. I'd like to up this and find a HRM that can be integrated to my iphone with its results, too, if it's possible.

I've seen a handful on Amazon, but I was wondering if anyone here has reviews on what is and isn't good? What they've been using and definitely loved?