Show HN: Heart Rate Zones Plus – The first iOS app I ever developed
23 comments
·April 28, 2025tobias5
throwanem
I like this visualization! I'm not doing a kind of training these days where it would be useful for me, but I wish I'd known about something like it when I was.
Do you support Apple watch? I never actually targeted that or owned one (I like a much more stylish smartwatch!) and thus don't immediately know how to spot that integration on an App Store detail page, hence the need to ask. But I get the sense a lot of folks who do train seriously like to do that with an Apple watch as primary or only device, and I could see enough utility in getting something like this kind of view in effective real time, to make the integration possibly worth considering. (If not already present! Or who knows, maybe Apple watches natively do that and now I know what the "heart rate push" feature on mine is imitating... ;)
bryan0
The Apple watch Workout app has a heart zone view while you're working out, but I don't think it has a workaround summary of how much time you spent in each zone.
serial_dev
Congrats on the launch! I really would have thought it’s already part of the iOS built in apps!
You mentioned it’s your first app. Did you vibe code your way through it or did you heavily use AI?
I played around with Swift SwiftUI and I felt that AI helped me a lot in contrast to my day to day job, humongous code base, I can’t get AI to get those mythical 100x productivity gains, more like 0.37x, but for new projects it’s been great, so I was wondering…
cyberpunk
Okay, admittedly I'm somewhat of a greybeard by this point... However... I thought that vibe coding was .... exactly heavily using AI...
I know this not the place; but what exactly is your definition of 'vibe coding' since you've used it with such confidence in your comment perhaps you can enlighten this programmer..
CharlesW
> I really would have thought it’s already part of the iOS built in apps!
Between the Apple Watch and Fitness app, you can see your heart rate zone during a workout, and then review workout heart rates/zones over time afterward. https://support.apple.com/guide/watch/view-heart-rate-zones-...
tchock23
Sort of. You can only see your real-time heart rate on your phone when you're doing a cycling workout for some weird reason. Otherwise you have to awkwardly look at your watch if you're walking/running.
pbreit
Can an iPhone app figure out your blood pressure (with sufficient reliability)?
brandonb
Not now, but future Apple Watches are rumored to track blood pressure through analysis of pulse transit time: https://www.empirical.health/blog/apple-watch-blood-pressure...
kube-system
... if you connect a blood pressure monitor, yes.
This app isn't figuring out your heart rate with just the phone's hardware. It is displaying heart rate data from Apple Fitness, which comes from heart rate sensor data (e.g. the one on an Apple Watch)
tchock23
Nicely done! UI is clean and I really like that you give different options on how to calculate the zones since most apps just take the simplified % of max HR for zone calculations.
jpc0
More an organisational thing but, what is the long term sustainability plan for this project. Apple Developer Program isn’t free and apple isn’t exactly well known for keeping stable APIs.
If the answer is “until I don’t want to do it anymore” that is perfectly fine but then can there be a commitment to open sourcing (if it isn’t already) when you make that decision?
throwanem
I seriously doubt Apple will casually abandon HealthKit. They are not Google, and I'm sure the contracts underpinning MFi and similar marks for major partners have savagely punitive terms that would enable those partners to recover in any such case.
jpc0
Not what I was referring to, hope this clarifies but apple seems willing to change the API which would require dev time to implement, ie this isn’t a project you can stick on the app store and ignore, it will require continuous effort and cash to keep there and compatible.
As an individual developer is the owner of the app and code I just want to know if the app will still exist in a year and be functional, otherwise I am not interested regardless of me liking the app idea.
If OP would like to charge money or accept donations or whatever they would like to do that is fine, but right now those questions are unanswered.
kccqzy
I would prefer an adaptive approach where the user also enters perceived difficulty and the app learns the correlation between heart rate and perceived difficulty to figure out the zones. I consistently have high heart rate during exercise: a normal walk might get my heart rate to 130, and a moderate run (10:30/mile) might get my heart rate to 180. A very fast run gets my heart rate to 215 (this is beyond the max measurement of the Apple Watch which is 210bpm; I had to use a Garmin HRM to get this measurement). I don't really trust the zones information iOS calculates by default, and it seems like I also can't trust the zones in this app. Switching to the Karvonen method makes the numbers look believable, but I'm not sure where the intensity comes from.
maperz
Congratulations on your first App! I like the clean design and the simple configuration.
I would love to have a widget that shows my progress in the zones. Ideally this could be configured to e.g. only show progress in Zone 2 if thats my current training goal.
Keep up the good work and thanks for sharing!
ra7
Looks clean!
Does the Health app not allow you to automatically grab resting heart rate and max heart rate? I'm not sure why I would manually set those values in settings when they are already tracked in Health.
nikitoci
The ability to set max heart rate manually would be appreciated, neither of five available formulas provide accurate estimates at least for me.
nonameiguess
I can't tell from reading the listing if this is a feature or not, but if not, you should add the ability to set custom targets that match your real heart rate zones rather than relying on the naive population estimators that Apple gives you, along with more important metrics like LT1 and LT2 thresholds and VO2 max. Ideally, this would be a feature of the exercise tracker itself, but getting it in a data rollup app is better than nothing.
I build this iOS app because I wanted to get an overview of my time in zones per week without checking zones after every workout manually - Now I'm looking for feedback.
Description: Track time in heart rate zones. Track per day, week, month, 7 days and 30 days time period and how much time you spend in each zone. Set goals & visualize progress. Get details about heart rates zones of your workouts.
Features: Custom time periods, Workout to zone attribution to get a feeling which sport attributed most to each zone, Multiple zone calculation methods, Set personal time goals for any zone, Workout breakdown
Pricing: Free
Privacy: Nothing is tracked or send somewhere. Data is just on your device.
Any feedback and features request is appreciated.
Download: https://apps.apple.com/us/app/heart-rate-zones-plus/id674474...
Video of the app in action: https://www.youtube.com/shorts/-qtHxEdMEv0