Displaying only time from a Date object in Swift/SwiftUI

Question

I've been working with displaying audio duration with ending time. One of the good Stack Overflow developers suggested this solution.

Hence, I've added this in my view:

struct ContentView: View {
    @ObservedObject var viewModel = MyViewModel() //<- here
    var body: some View {
        VStack {
            
            Text(viewModel.endTime) //<- here
            
        }
    }
}

This is the code in my viewModel:

class MyViewModel: ObservableObject {
    @Published var endDate: Date? 
    var endTime: String{
        endDate == nil ? "":endDate!.description 
    }

    func play(){
        let path = Bundle.main.path(forResource: "song", ofType:"mp3")!
        let url = URL(fileURLWithPath: path)
        do {
            player = try AVAudioPlayer(contentsOf: url)
            
            endDate = Date() + player.duration
            if player.isPlaying{
                
                player.pause()
                
            }
            else{
                player.play()
                
            }
            isPlaying = player.isPlaying
        }catch{print("error")}

But I'm getting the wrong time (not the system time) but with the correct date. I want to display only the correct time without date.

Answer 1

To display a formatted date, you'll probably want to use DateFormatter:

let dateFormatter = DateFormatter()
dateFormatter.dateStyle = .medium
dateFormatter.timeStyle = .none
 
let date = Date(timeIntervalSinceReferenceDate: 118800)
 
// US English Locale (en_US)
dateFormatter.locale = Locale(identifier: "en_US")
print(dateFormatter.string(from: date)) // Jan 2, 2001

Source: https://developer.apple.com/documentation/foundation/dateformatter

(Note that creating a DateFormatter is known to be an expensive operation so be careful about creating them too often)

You have a couple of logic errors in your view model as well. Here's an example of how to handle this:

struct ContentView : View {
    @ObservedObject private var vm = MyViewModel()
    
    var body: some View {
        Button(action:{
            vm.play()
        } ) {
            Text(vm.isPlaying ? "Stop" : "Play")
        }
        Text(vm.endTime)
    }
}

class MyViewModel: ObservableObject {
    @Published var endDate: Date?
    @Published var isPlaying = false
    
    var player = AVAudioPlayer()
    var dateFormatter = DateFormatter()
    
    var endTime: String{
        guard let endDate = endDate else {
            return ""
        }
        dateFormatter.dateStyle = .none
        dateFormatter.timeStyle = .medium
        return dateFormatter.string(from: endDate)
    }

    func play(){
        do{
            if player.isPlaying {
                player.pause()
            } else {
                let path = Bundle.main.path(forResource: "All Of Me Final Mix", ofType:"mp3")!
                let url = URL(fileURLWithPath: path)
                player = try AVAudioPlayer(contentsOf: url)
                endDate = Date() + player.duration - player.currentTime
                player.play()
            }
            isPlaying = player.isPlaying
        } catch {
            print("error: \(error)")
        }
    }
}