Blood pressure app recommendations for iPhone

I phones are not capable of monitoring BP but there may be third party apps on the Apple App Store that will allow you to manually enter your readings.

I use a BP cuff that has a companion app that receives the measurements from the cuff via Bluetooth. The app then tracks by BP, reminds me to take a reading and provides analytics. My BP cuff is made by Withings and I very pleased with its ease of use and longevity.

Like Jeff, I've used Withings and found them to be excellent. For a less expensive option, you might look at the ones by Omron. The app is less slick, but it works quite well. It syncs with Health.