Hi, this is my first post and I first wanted to thank Paul and everyone for creating and maintaining such a wonderful community! (Also, please let me know if I'm breaking any code of conduct or any kind of improvements on how I formatted my question)

I was tackling Day 28's challenge problems. And, here's what I've successfully done so far,

UI Changes

1. Replaced VStack with Sections.

2. Got rid of the Toolbar and Alert - replaced it with a "Calculate" button inside form, where clicking on "Calculate" will display sleep time as a text value (sleepTimeDisplay).

Added methods

1. Added a resetForm function, which is called when the user clicks on "Reset". It wipes all user inputs and restores default values.

2. Added a resetSleepTimeDisplay function, which resets sleepTimeDisplay. In my code, I called it whenever there's a change in user input, to encourage users to click on "calculate" with every new input.

Room for Improvements?

I think that's all the features I wanted to build for this project, and it's working as intended. But I do think there are many improvements that can be made in the code. I am definitely not too happy about how I used three individual onChange() to call resetSleepTimeDisplay for every section. I did read up on how to pass multiple parameters on onChange, but I couldn't successfully write the code. It would be really helpful to find a way to call resetSleepTimeDisplay with just one line of code, instead of calling it with onChange for every section! Thank you!

struct ContentView: View {
    @State private var sleepAmount = 8.0
    @State private var coffeeAmount = 0
    @State private var wakeUp = defaultWakeTime

    @State private var sleepTimeDisplay = ""

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

    var body: some View {
        NavigationView {
            Form {
                Section {
                    Picker("How much coffee did you drink", selection: $coffeeAmount) {
                        ForEach(1..<6) {number in
                            Text(number == 1 ? "1 cup" : "\(number) cups")
                        }
                    }
                    .pickerStyle(.segmented)
                } header: {
                    Text("How much coffee did you drink?")
                        .font(.subheadline)
                }
                .onChange(of: coffeeAmount) {newValue in
                    resetSleepTimeDisplay()
                }

                Section {
                    Stepper("\(sleepAmount.formatted()) hours", value: $sleepAmount, in: 0...24, step: 0.5) {_ in
                    }
                } header: {
                    Text("How much sleep do you want?")
                        .font(.subheadline)
                }
                .onChange(of: sleepAmount) {newValue in
                    resetSleepTimeDisplay()
                }

                Section {
                    HStack {
                        Text("I'll wake up at")
                        DatePicker("Please enter a time", selection: $wakeUp, displayedComponents: .hourAndMinute)
                            .labelsHidden()
                        .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .trailing)
                    }

                } header: {
                    Text("When do you want to wake up?")
                        .font(.subheadline)
                }
                .onChange(of: wakeUp) {newValue in
                    resetSleepTimeDisplay()
                }

                Button("Calculate", action: calculateBedtime)

                Text(sleepTimeDisplay == "" ? "Tap Calculate to get your new bedtime." : "Your ideal bedtime is \(sleepTimeDisplay)")

                Button("Reset") {
                    resetForm()
                    resetSleepTimeDisplay()
                }
            }
            .navigationTitle("BetterRest")
        }
    }

    func calculateBedtime() {
        do {
            let config = MLModelConfiguration()
            let model = try SleepCalculator(configuration: config)

            let sleepTimeComponent = Calendar.current.dateComponents([.hour, .minute], from: wakeUp)

            let hour = (sleepTimeComponent.hour ?? 0) * 3600 // in seconds
            let minute = sleepTimeComponent.minute ?? 0 * 60 // in seconds

            let prediction = try model.prediction(wake: Double(hour + minute), estimatedSleep: sleepAmount, coffee: Double(coffeeAmount))

            let sleepTime = wakeUp - prediction.actualSleep

            sleepTimeDisplay = "\(sleepTime.formatted(date: .omitted, time: .shortened))"

        } catch {
            sleepTimeDisplay = "Sorry, there was an error calculating your bedtime."
        }

    }

    func resetForm() {
        sleepAmount = 8
        coffeeAmount = 0
        wakeUp = ContentView.defaultWakeTime
    }

    func resetSleepTimeDisplay() {
        sleepTimeDisplay = ""
    }
}