Read and Write Info in a Swift App
by Ben Church
How to read and write Mindful Minutes from iOS's HealthKit with Swift
I took the time to figure out how to read and write from HealthKit and so you don't have to!
I admittedly love the road Apple has been going with their iOS SDK's. (Their hardware not so much). Apple tree's focus on security has immune information technology to become a reliable company to trust your sensitive information with. This has allowed iPhones to make headway as the device best suited to host medical data. As a result, they're also the best device to make software that interfaces with a user'southward sensitive personal info.
With this in mind, I believe it'south essential to know how to read and write from Apple'due south HealthKit and so that nosotros every bit developers can leverage the position Apple has put itself in. So today's tutorial is going to focus on Reading and writing Mindful Minutes from Apple'southward HealthKit.
By the cease of this tutorial, you will accept learned how to:
- Setup a bones iOS app
- Asking permission to read and write data from HealthKit
- Read and query data from HealthKit
- Write data dorsum to HealthKit
Alright let'south jump into setting up the XCode Project. ?
Setup the Skeleton
Every great project starts from the aforementioned screen (if yous're just looking for code, then you can skip this section).
1. Create a new project
Let'due south kick this off by creating a new Single View App project in XCode.
> Project
ii. Include HealthKit
Once we've created the project, we demand to bundle HealthKit with our application:
and update the info.plist file to contain what the user will meet when nosotros ask for their permission to access their data.
Add together the following xml to the info.plist file:
3. Create a basic UI
To finish up the setup, nosotros will want to create a uncomplicated UI that volition let us to view the data we have read from the HealthKit and provide an activity that volition allow u.s. to trigger a write back to the HealthKit.
Start by opening the storyboard and:
- Add a label and connect it to the
ViewController.swiftfile under the proper namemindfulMinuteLabel - Add a button and connect information technology to an
Actionin theViewController.swiftfile titledaddMinuteAct
Breath some life into it…
Now that we've put the infrastructure in place, it'southward time to write the logic that will do all the interfacing with HealthKit we have been talking nigh.
1. Ask for permission
Every HealthKit app needs to explicitly ask for a user'southward permission for every blazon of read and write information technology needs to do. To accomplish this, we desire to ask on viewDidLoad for permission to read Mindful Sessions and for permission to write Mindful Sessions.
Now when the app is run, you should be prompted by the screen below.
If you are running this right at present, you volition want to comment out self.retrieveMindfulMinutes() 2. Reading Mindful Minutes
And so far this has been very straight frontward: Create UI, enquire for permission. Next we're going to come into reading from HealthKit. While Apple tree gives us a powerful UI, it's not necessarily intuitive. And so I'm going to begin by showing you the code, and so I'll explain it after.
The query nosotros execute to retrieve our Mindful Sessions can be cleaved into 4 components:
one. Sort by End Date
The beginning section of this lawmaking is optional but useful to know. What we are doing is asking the query to give united states the list of Mindful Sessions ordered past their stop time with the well-nigh recent session being first.
2. Utilize the Predicate to define the Query
The next portion of our code deals with the actual specifics of a "query": What subset of data are nosotros looking for. In our instance, we want all samples from the last 24 hours.
3. Compose and Run your Query
Finally, we desire to combine the sortDescriptor, the predicate, and the sampleType we want from the HealthKit together with the role that will handle whatever is returned by the query (resultsHandler). After this is all equanimous into a HKSampleQuery, the merely stride left is to execute it!
4. Aggregating the session information and updating the UI
Within the part we defined equally our resultsHandler in the previous section, nosotros want to:
- Become the total time for each Mindful Session
- Sum all total times to get the total number of Mindful minutes over the concluding 24 hours.
- Update our characterization with the total.
This should all be relatively straightforward if y'all understand the concepts of map and reduce. If these are new to you, I recommend taking the time to larn them. They are found in most programming languages and are a great introduction into the wonderful world of Functional Programming.
The just piece that may non exist straightforward is why nosotros wrap
self.meditationMinutesLabel.text = labelText in DispatchQueue.main.async . The reason we practice this is and then nosotros tin update the UI without blocking the master thread of the application. This is a convention enforced by the compiler itself!
Writing the information
In the above, nosotros went over how to read from HealthKit. But how do nosotros write data to it? Thankfully the process is a lot simpler. The following code is going to:
- Consummate
addMinuteActfunction we added during setup, and as a consequence, the balance of the application. - Create a
MindfulSessionof 1 infinitesimal starting now - Save this new
MindfulSessionto the HealthKit - Update the label to reflect the new total Mindful Minute count
Start it upwardly!
With all that finished and the lawmaking written, you should be able to kickoff this app in your simulator, have the request to read and write from your HealthKit, and brainstorm viewing how often you've Meditated in the final 24 hours!
Wrap up
At the beginning of this project, I was very excited to jump into HealthKit. I do run into it being positioned to modify the mode we and others collaborate with sensitive personal information.
Notwithstanding, I call up that Apple tree, in dissimilarity to other platforms, makes their API's a little too hard to observe both through their documentation and through XCode. Hopefully they volition improve this experience, merely until they practise, learning how to utilise HealthKit can be an practice in pulling teeth.
I hope this post saves you from having to stumble around and tin can get yous aircraft your products faster!
? This is open source! you tin find it here on Github
❤️ I simply write about programming and remote work. If yous follow me on Twitter I won't waste product your time.
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Source: https://www.freecodecamp.org/news/read-write-mindful-minutes-from-healthkit-with-swift-232b65118fe2/
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