SwiftUI: How can I auto-update the song title in a Text view when the song changes?

One common issue is that your UI isn’t updating because the property you’re changing isn’t linked (via property observers) to your SwiftUI view. In SwiftUI you need to publish any property changes that should update the view. Currently, changing your global variable songTitle does nothing to trigger a view update.

Below is an updated example using an @Published property inside your ObservableObject:

Updated Code Example

SWIFTCopied
import SwiftUI
import MediaPlayer

class MusicMonitor: ObservableObject {
    // Use @Published on the property so that SwiftUI will update affected views.
    @Published var songTitle: String = "No song playing"
    
    private let player = MPMusicPlayerController.systemMusicPlayer
    
    init() {
        // Start receiving notifications.
        NotificationCenter.default.addObserver(
            forName: .MPMusicPlayerControllerNowPlayingItemDidChange,
            object: player,
            queue: OperationQueue.main) { [weak self] _ in
                self?.updateCurrentSong()
                print("Song changed: \(self?.songTitle ?? "No song playing")")
        }
        
        // Enable notifications.
        player.beginGeneratingPlaybackNotifications()
        updateCurrentSong() // Get initial song
    }
    
    private func updateCurrentSong() {
        // Always update on the main thread.
        DispatchQueue.main.async { [weak self] in
            guard let self = self else { return }
            // Update published property.
            self.songTitle = self.player.nowPlayingItem?.title ?? "No song playing"
        }
    }
    
    deinit {
        player.endGeneratingPlaybackNotifications()
    }
}

SwiftUI View Example

Then, in your SwiftUI view, you can observe changes by using the @ObservedObject or @StateObject property wrapper:

SWIFTCopied
struct ContentView: View {
    // Use @StateObject when creating the instance in this view.
    @StateObject private var musicMonitor = MusicMonitor()
    
    var body: some View {
        Text(musicMonitor.songTitle)
            .padding()
    }
}

Key Points

• @Published: Mark the variable that you want to update the UI when it changes.
• ObservableObject: The class conforms to ObservableObject so that SwiftUI can monitor it.
• @StateObject/@ObservedObject: Use these in your views to link to your MusicMonitor so that updates trigger view refresh.
• Main Thread: Ensure updates occur on the main thread when updating UI-related state.

By following this pattern, your Text() view will automatically update whenever the current playing song changes on the device.