I want to make a metronome BPM app through SwiftUi, but the sound is not consistent when the screen is turned off

Question

I'm currently building a metronome app with SwiftUI to play audio at a desired BPM.

I’ve active background mode and if the screen is on, the sound will be constant even if I leave the app.

However, when I turn off the screen, the sound stops and starts to delay or slow down.

1.AVAudioSession's rate value is not applied.

2.Timer.scheduledTimer(withTimeInterval: interval, repeats: true) { _ in
            audioPlayer?.play()
        }

I don't know if the interval value (60.0 / tempo) of this timer doesn't apply.

If anyone has encountered a case like this and solved it, please give me some advice.