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)

[Read more…]

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.

[Read more…]

Updated 21 March 2025 for iOS 18.

For a more modern version using SwiftUI to visualise the data, see How to Fetch and Display HealthKit Data with HKAnchoredObjectQuery

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…]

For todays tutorial we will look at reading characteristic data from HealthKit. This is one of several ways in which we can read data, with the other ways being queries and long-running queries. We will investigate queries and long-running queries at another time.

Direct method calls can be used to the HKHealthStore to read characteristic data. These items stored in HealthKit do not require a query to be made. These are characteristic types of data such as sex, date of birth, and blood type, to name a few. The reason for this is that these types of data do not change over time. For example, your birthday remains constant.

You can access characteristic data directly through the health store. In a previous tutorial we covered how to setup Apple HealthKit. We will continue on from this project, which you can download here.

In that previous tutorial we requested permissions for stepCount and biologicalSex. Out of these two, biologicalSex is the only one which is characteristic data. We will look at how we can request this data from Apple HealthKit. [Read more…]

In the final part of this tutorial series we will make some slight adjustments to the graph, and then provide the ability to record your weight in HealthKit.

You can either jump back to the beginning where we created a line graph with Paintcode, start on step 2, or begin here by downloading the project as we left it at the end of the last tutorial. [Read more…]