DevFright

HKHealthStore is the way you interact with HealthKit on a users device. It provides the necessary tools to gather permission from the user as well as provides ways to fetch characteristic data, save data, and delete data.

Today’s tutorial will be fairly brief. We will look at a few of the abilities that this class gives to you. Some of them we have already covered. If you want to know how to save an object to Apple Health, check out this tutorial, or this tutorial. If you want to read characteristic data from the health store, that post is for you. [Read more…]

In our last tutorial we looked at how to save quantity samples with HealthKit. Today we will look at how to save category samples. Just so you are aware of the difference, quantity samples contain a numeric value such as your weight, number of steps taken between 2 points of time, amongst many other things. A category sample is a type where information can be represented from a short list of options such as tracking your sleep. You are either asleep or you are not.

If we look at the sleep analysis category we can see in the documentation that there are 3 options. You are in bed, you are asleep, or you are awake. It is up to you, the developer, to decide how frequent the samples are recorded. An explanation of how to record category samples for sleep is found in the documentation.

In short, out of the 3 states you would record the time that the user was in bed, and then create a second sample with its own timings to show when they were asleep or not. The drawing below shows that the user was in bed for a few hours, slept for some of that, then got out of bed, and then got back in to bed, and then fell asleep, woke up, stayed in bed, fell back asleep, woke up, and then got out of bed. In bed shouldn’t be recorded as the opposite of sleep (ie, in bed is in bed, and not awake).

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In earlier tutorials we have focussed on reading information with HealthKit. There are a number of queries that can be used to request information in a variety of ways. In this tutorial we will work on saving information with HealthKit.

Saving data to the health store with HealthKit follows a general procedure which has just 4 steps.

The first step is to find the identifier for the type of data you want to store. For this tutorial we will save body mass. In a later tutorial we will look at saving workouts, and other more complex data types such as step counts where there are more than just 1 reading per day. [Read more…]

Yesterdays tutorial was about the HKActivitySummaryQuery which allows your app to seek permission from the user to access the exercise ring, and all history and details associated with it. The query is one of the simplest available in HealthKit. The only parameter you can pass in is a predicate to specify a range of dates, or a single date. If you set it to nil, it will read all activity of the user.

In todays tutorial we will look at the long-running query that is available for HKActivitySummaryQuery. This particular version of the query keeps running in the background and monitors for changes. Each time the health store is updated with new data; either stand, exercise, or active calories; the update handler will be called which will allow you to refresh your views, should you need to.

As well as looking at the query, we will also add a UIView to the storyboard and set this up as a HKActivityRingView to display the rings on the view. [Read more…]

The HKActivitySummaryQuery is useful for apps that are interested in what the user has done each day, in regards to exercise, stand hours, active calories, etc… The query can be used to query a single day, or a range of days.

The easiest way to think about this query is to look at the activity ring, or a collection of activity rings as pictured here. Apple Watch owners will be very aware of what each ring represents. This class allows you to fetch the data that builds up this ring, but also pass it to the HKActivityRingView to represent those numbers in a familiar format to Apple Watch users. For those wanting to use the Apple Watch version of the ring, Apple also has made available WKInterfaceActivityRing.

This tutorial will focus on the query and fetching the data. We might touch upon the activity ring view in a future tutorial, but for now we will focus on executing the query to fetch the available data. [Read more…]

The HKSourceQuery provides a way for you to request what apps and devices are saving a specified sample type to the health store. This tutorial will be one of the shorter ones as there isn’t too much that can be done with this particular query.

A read through of the documentation shows that the HKSourceQuery simply has an init method, and nothing else.

init(sampleType: HKSampleType, 
samplePredicate objectPredicate: NSPredicate?, 
completionHandler: @escaping (HKSourceQuery, Set<HKSource>?, Error?) -> Void)

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We looked previously at the basic HKSampleQuery and the HKAnchoredObjectQuery. Both provided ways to query samples in HealthKit and work with data that the user had provided permission for.

The next query we will look at is the HKStatisticsQuery. This query is particularly interesting to those who want to calculate sum, minimum, maximum, or average values.

Lets begin by downloading the project from where we left off last time.

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The HKAnchoredObjectQuery provides a useful way to keep tabs on what has changed for a particular sample type. It provides us with both the ability to receive a snapshot of data, and then on subsequent calls, a snapshot of what has changed. Alternatively you can create the initial snapshot of samples, and then continuously monitor as a long-running query which notifies you each time a new sample is added or when a sample is deleted.

For this tutorial we will continue on from an earlier tutorial, and add more functions that will allow us to test the HKAnchoredObjectQuery class. Go ahead and download the latest version of the project and open it in Xcode. [Read more…]

In the last tutorial we covered reading characteristic data from HealthKit. Characteristic data is read by accessing direct methods on the health store. These queries are simple because items like date of birth and biological sex do not typically change. However, there are many data types stored in Apple Health that do change such as step counts, heart rate, body mass, and so on. For these types of data Apple allows us to create queries so that we can fetch the data we want.

Many of your requests to HealthKit will be done by using a query. Queries allow you to fetch a snapshot of data from the HealthKit store. There are eight different types of queries that you have available to use with HealthKit. This tutorial will cover the HKSampleQuery. We will look at each other type of query in separate posts. [Read more…]