Here is my code to change the textField to a picker. I get the error "Contextual closure type '() -> TupleView<(ForEach<Range<Int>, Int, _>, Text)>' expects 0 arguments, but 1 was used in closure body" and "Generic parameter 'Content' could not be inferred". Not sure what to do here

Text("Desired Amount of Sleep")
    .font(.headline)

Picker(selection: $sleepAmount,  label: Text("")){
    ForEach(1..<hours.count)
    Text(self.hours[$0])
                    }

You need brackets for your ForEach:

Picker(selection: $sleepAmount,  label: Text("")){
    ForEach(1..<hours.count) {
        Text(self.hours[$0])
    }
}

did that, and I get following error: "No exact matches in call to initializer "

I am also trying to call sleepTime at the bottom of the app , but it is inside of calculateBedTime(). How do I declare the variable so that they can be used elsewhere? Also, do I have to also declare all the other variables: components, hour, minute, prediction?

import SwiftUI
struct ContentView: View {
    @State private var sleepAmount = 8.0
    @State private var wakeUp = defaultWakeTime
    @State private var coffeeAmount = 1

    @State private var alertTitle = ""
    @State private var alertMessage = ""
    @State private var showingAlert = false

    @State private var model = SleepCalculator()

    @State private var components = Calendar.current.dateComponents([.hour, .minute], from: wakeUp)
    @State private var hour = (components.hour ?? 0) * 60 * 60
    @State private var minute = (components.minute ?? 0) * 60
    @State private var  prediction = try
        model.prediction(wake: Double(hour + minute) ?? 8, estimatedSleep: sleepAmount, coffee: Double(coffeeAmount))
    @State private var sleepTime = wakeUp - prediction.actualSleep

    var hours = [1..<9]
    var body: some View {
        NavigationView{
            Form{
                VStack(alignment: .leading, spacing: 0) {
    Text("When do you want to wake up?")
                    .font(.headline)
    DatePicker("Please enter a time", selection: $wakeUp,  displayedComponents: .hourAndMinute)
        .labelsHidden()
        .datePickerStyle(WheelDatePickerStyle())
                }
VStack(alignment: .leading, spacing: 0)
                {
Text("Desired Amount of Sleep")
    .font(.headline)

//    Picker(selection: $sleepAmount,  label: Text("")){
//        ForEach(1..<hours.count) {
//            Text(self.hours[$0])
//        }
//    }

//    Stepper (value: $sleepAmount, in: 4...12, step: 0.25){
//        Text("\(sleepAmount, specifier: "%g") hours")
//            }
                }
VStack(alignment: .leading, spacing: 0) {
        Text("Daily coffee intake")
            .font(.headline)
        Stepper (value: $coffeeAmount, in: 1...20){
        if coffeeAmount == 1 {
                Text ("1 cup")
                    } else {
        Text("\(coffeeAmount) cups")
                    }
                }
                }

    VStack(alignment: .leading, spacing: 0){
        Text("Your Ideal Bed Time is:\(sleepTime)")
            .font(Font.title.weight(.bold))
        //Text("\(sleepTime")
                }
        }
            .navigationTitle("Better Rest")
//          .navigationBarItems(trailing:
//            Button(action: calculateBedtime){
//                Text("Calculate")})
//            .alert(isPresented: $showingAlert) {
//                Alert(title: Text(alertTitle), message: Text(alertMessage), dismissButton: .default(Text("OK")))}

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

        let components = Calendar.current.dateComponents([.hour, .minute], from: wakeUp)
        let hour = (components.hour ?? 0) * 60 * 60
        let minute = (components.minute ?? 0) * 60
        do{
            let prediction = try
                model.prediction(wake: Double(hour + minute), estimatedSleep: sleepAmount, coffee: Double(coffeeAmount))

            let sleepTime = wakeUp - prediction.actualSleep

            let formatter = DateFormatter()
            formatter.timeStyle = .short

            alertMessage = formatter.string (from: sleepTime)
            alertTitle = "Your ideal bedtime is ..."

        } catch {

alertTitle = "Error"
alertMessage = "Sorry, there was a problem calculating your bedtime."
        }
        showingAlert = true
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

Do I make the @State variables?