HeartRateMonitor with HealthKit

iOS example based on the Xamarin.Mac HeartRateMonitor by abock, with HealthKit code by @lobrien

The HeartBeat, HeartBeatEventArgs, HeartRateMonitorLocation classes are unchanged from Aaron's Xamarin.Mac app. The HeartRateMonitor class only required namespace changes. The CoreBluetooth APIs work identically across OS X and iOS.

It has been modified from the Xamarin.Mac sample in the following ways:

• A list of heart rate monitor devices is no longer presented; the code automatically chooses the first device it 'finds'.

• The heart-beat animation hasn't been converted yet (I hope to add the animation to this sample soon).

• I've commented out some unsafe code from the Mac version. This code still works in iOS (if you 'tick' Project > Options > Build > General > Allow 'unsafe' code) but because many .NET devs aren't familiar with this I've replaced it with a safe version. If you're wondering why you'd use the unsafe version, Aaron says:

(generally) alloc + copy is expensive. You're allocating that array on the heap each time, then copying memory to it, then reading it vs just reading the original memory. The unsafe dereference/read avoids both, which can be critical in fast paths

• Added HealthKit support for iOS 8! When the app starts it requests permission to write to HealthKit. Then once connected to a device, every time you click on the Store in HealthKit button the app saves the currently displayed heart rate to HealthKit.

A screenshot of the app running is shown here, with the HealthKit permissions screen that appears on app-startup:

The data looks like this inside Apple's Health app - it is graphed and can be drilled-down to the entry level

Authors

Aaron Bockover, Larry O'Brien, Craig Dunn