Time Turner

TimeTurner_ContentView.swift

import SwiftUI

struct ContentView: View {
    enum timeUnits: String, CaseIterable, Identifiable {
        var id: String { self.rawValue }
        case seconds = "seconds"
        case minutes = "minutes"
        case hours = "hours"
        case days = "days"
    }
    
    @State private var input = ""
    @State private var inputUnit: timeUnits = .seconds
    @State private var outputUnit: timeUnits = .seconds
    
    var inputInSeconds: Double {
        let totalSeconds = Double(input) ?? 0
        
        switch inputUnit {
        case .seconds:  return totalSeconds
        case .minutes:  return totalSeconds * 60
        case .hours:    return totalSeconds * 3600
        case .days:     return totalSeconds * 86_400
        }
    }
    
    var convertedTime: Double {
        switch outputUnit {
        case .seconds:  return self.inputInSeconds
        case .minutes:  return self.inputInSeconds / 60
        case .hours:    return self.inputInSeconds / 3600
        case .days:     return self.inputInSeconds / 86_400
        }
    }
    
    var body: some View {
        NavigationView {
            Form {
                Section(header: Text("Time to convert")) {
                    TextField("Enter an amount to convert…", text: $input)
                        .keyboardType(.decimalPad)
                    
                    Picker("Input Unit", selection: $inputUnit) {
                        ForEach(timeUnits.allCases) {
                            Text($0.rawValue).tag($0)
                        }
                    }
                    .pickerStyle(SegmentedPickerStyle())
                }
                
                Section(header: Text("Converted Time")) {
                    Text("\(convertedTime, specifier: convertedTime.truncatingRemainder(dividingBy: 1) == 0 ? "%.f" : "%.5f")")
                    
                    Picker("Output Unit", selection: $outputUnit) {
                        ForEach(timeUnits.allCases) {
                            Text($0.rawValue).tag($0)
                        }
                    }
                    .pickerStyle(SegmentedPickerStyle())
                }
            }
            .navigationBarTitle("Time Turner")
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
            .previewDevice("iPhone 11 Pro")
    }
}

Another iteration on this, just for fun: https://gist.github.com/k-mao/e7a863937b9d06cfec4ed0ba156be743