Screenshot

Building a basic layout

// Setting Up Properties
@State private var wakeUp = Date.now
@State private var sleepAmount = 8.0
@State private var coffeeAmount = 1

// Creating Date Picker for Wake Up Time
DatePicker("Please enter a time", selection: $wakeUp, displayedComponents: .hourAndMinute)
    .labelsHidden()

// Implementing Stepper for Desired Sleep Amount
Stepper("\\(sleepAmount.formatted()) hours", value: $sleepAmount, in: 4...12, step: 0.25)

// Adding Stepper for Coffee Intake
Stepper(coffeeAmount == 1 ? "1 cup" : "\\(coffeeAmount) cups", value: $coffeeAmount, in: 1...20)

// Adding Button to Navigation Bar
.navigationTitle("BetterRest")
.toolbar {
    Button("Calculate", action: calculateBedtime)
}

Connecting SwiftUI to Core ML

// Importing Core ML
import CoreML

do {
		// Creating an Instance of the Core ML Model
    let config = MLModelConfiguration()
    let model = try SleepCalculator(configuration: config)
    
		// Extracting Hour and Minute Components from Date
		let components = Calendar.current.dateComponents([.hour, .minute], from: wakeUp)
		let hour = (components.hour ?? 0) * 60 * 60
		let minute = (components.minute ?? 0) * 60

		// Making a Prediction using the Core ML Model
		let prediction = try model.prediction(wake: Double(hour + minute), estimatedSleep: sleepAmount, coffee: Double(coffeeAmount))

		// Calculating Bedtime and Displaying in Alert
		let sleepTime = wakeUp - prediction.actualSleep
		
		alertTitle = "Your ideal bedtime is…"
		alertMessage = sleepTime.formatted(date: .omitted, time: .shortened)	

} catch {
    // Handle error
}

Cleaning up the user interface

// Computed Property for Default Wake-Up Time
@State private var wakeUp = defaultWakeTime

static var defaultWakeTime: Date {
    var components = DateComponents()
    components.hour = 7
    components.minute = 0
    return Calendar.current.date(from: components) ?? Date()
}