SwiftUI: Alcohol Content Check: HealthKit, and CareKit Walk into a Bar š»Ā iOS
- Di Nerd Apps
- Mar 19, 2023
- 3 min read
Updated: Mar 25, 2023
Learn how to create a fun and easy SwiftUI app that utilizes HealthKit and CareKit to monitor usersā blood alcohol content (BAC)
Welcome, dear beginners and fellow programmers, to a journey where weāll be brewing up a delightful concoction of SwiftUI, HealthKit, and CareKit! In this article, weāll create an app to measure usersā blood alcohol content (BAC). And donāt worry, our path will be paved with light, funny jokes to keep you engaged and entertained. Cheers! š„
Part 1: Prepping the Ingredients š
Before we start concocting our app, make sure you have the following:
A Mac running macOS Monterey or later
Xcode 13 or later
An Apple Developer account (to access HealthKit and CareKit)
A taste for fun and an appetite for learning! š½ļø
Step 1: Create a New SwiftUI Project
Fire up Xcode, and create a new project using the āAppā template under āMultiplatformā or āiOS.ā Name your project āBACMonitorā and ensure āInterfaceā is set to āSwiftUIā and āLife Cycleā to āSwiftUI App.ā
Step 2: Import HealthKit and CareKit
In your projectās āSigning & Capabilitiesā tab, click on ā+ Capabilityā and add āHealthKitā and āCareKitā to your app. Youāll need to sign in with your Apple Developer account to access these frameworks.
Now that weāre all set, letās dive into the world of SwiftUI, HealthKit, and CareKit!
Part 2: Mixing SwiftUI, HealthKit, and CareKit š¹
To create our BAC monitoring app, weāll develop a simple SwiftUI interface that displays usersā blood alcohol content and allows them to enter new BAC data.
Step 1: The SwiftUI Interface
First, letās create a simple SwiftUI interface with a TextField to input BAC data and a Text view to display the latest BAC value.
import SwiftUI
import HealthKit
struct ContentView: View {
@State private var bacInput: String = ""
@State private var latestBAC: Double = 0.0
@ObservedObject private var healthStore = HealthStore()
var body: some View {
VStack {
TextField("Enter your BAC", text: $bacInput)
.textFieldStyle(RoundedBorderTextFieldStyle())
.keyboardType(.decimalPad)
.padding()
Button("Submit BAC") {
if let bacValue = Double(bacInput) {
healthStore.addBACData(bacValue: bacValue)
bacInput = ""
}
}
.padding()
Text("Latest BAC: \(latestBAC, specifier: "%.3f")")
.padding()
}
.onAppear {
healthStore.getLatestBAC { result in
latestBAC = result
}
}
}
}
Step 2: Setting Up HealthKit
Now, letās create a HealthStore class to manage our interactions with HealthKit.
import HealthKit
class HealthStore: ObservableObject {
private let healthStore = HKHealthStore()
// ... more code to come
}
First, request authorization for BAC data:
init() {
requestAuthorization()
}
private func requestAuthorization() {
let typesToShare: Set = [HKObjectType.quantityType(forIdentifier: .bloodAlcoholContent)!]
let typesToRead: Set = [HKObjectType.quantityType(forIdentifier: .bloodAlcoholContent)!]
healthStore.requestAuthorization(toShare: typesToShare, read: typesToRead) { success, error in
if let error = error {
print("Error requesting authorization: \(error.localizedDescription)")
}
}
}
Next, create a function to save BAC data to HealthKit:
func addBACData(bacValue: Double) {
guard let bacType = HKObjectType.quantityType(forIdentifier: .bloodAlcoholContent) else { return }
let bacQuantity = HKQuantity(unit: HKUnit.percent(), doubleValue: bacValue)
let bacSample = HKQuantitySample(type: bacType, quantity: bacQuantity, start: Date(), end: Date())
healthStore.save(bacSample) { success, error in
if let error = error {
print("Error saving BAC data: \(error.localizedDescription)")
}
}
}
Lastly, create a function to fetch the latest BAC value:
func getLatestBAC(completion: @escaping (Double) -> Void) {
guard let bacType = HKObjectType.quantityType(forIdentifier: .bloodAlcoholContent) else { return }
let sortDescriptor = NSSortDescriptor(key: HKSampleSortIdentifierStartDate, ascending: false)
let query = HKSampleQuery(sampleType: bacType, predicate: nil, limit: 1, sortDescriptors: [sortDescriptor]) { _, samples, error in
if let error = error {
print("Error fetching BAC data: \(error.localizedDescription)")
completion(0.0)
} else if let sample = samples?.first as? HKQuantitySample {
let bacValue = sample.quantity.doubleValue(for: HKUnit.percent())
completion(bacValue)
} else {
completion(0.0)
}
}
healthStore.execute(query)
}
Part 3: The Last SipāāāConclusion šŗ
Cheers, fellow programmers! Youāve successfully crafted a fun and easy SwiftUI app that leverages HealthKit and CareKit to monitor usersā blood alcohol content. As you venture further into the world of iOS development, remember that this article is just a small sip of the vast ocean of possibilities. Keep exploring, and donāt be afraid to mix and match frameworks to create a delightful cocktail of apps! š¹
āWhen life gives you SwiftUI, HealthKit, and CareKit, make an app and monitor your BAC responsibly.āāāāProbably some wise developer at Happy Hour.

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