TapRate

Measure and calculate heart and respiratory rates using your iPhone or Apple Watch. All that's required is that you be able to feel a radial pulse rate or observe a respiratory rate, and then tap!
After a few recorded samples your rate will be displayed. Practice to become more proficient and accurate. If you're a healthcare professional (nurse, EMT, etc.) be sure to practice and compare your rates to those obtained using more traditional techniques and/or diagnostic measurement tools. Once you're comfortable using TapRate you'll be able to obtain heart and respiratory rates within seconds, which is way faster than waiting 15 or 30 seconds doing the same thing manually.