Pump up the volume! Control volume for audio on iOS using Swift
In most circumstances, you’ll want audio playback to use the volume settings on the device – users are typically not going to be happy if they turn down their volume, then hear something loud. But occasionally there may be a need to override the device settings – say an important alarm. We wouldn’t want to use this for sustained playback, but we recently wrote a function to play a specified sound, and optionally override volume to a specified level – 0 being silent and 1.0 being full-blast.
Here’s what the code looks like in Swift:
// Play a sound, optionally setting volume to the specified level
func playSound(audioURL: URL?, setVolume: Bool = false, level: Float = 1.0) {
if let audioUrl = audioURL {
do {
// Create an audio session for playback
try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback, with: .mixWithOthers)
try AVAudioSession.sharedInstance().setActive(true)
var volumeSlider: UISlider = UISlider()
var origVolume: Float = 0.0
if (setVolume) {
// Save the original volume level, then turn up the system volume
volumeSlider = (MPVolumeView().subviews.filter{NSStringFromClass($0.classForCoder) == "MPVolumeSlider"}.first) as! UISlider
origVolume = AVAudioSession.sharedInstance().outputVolume
volumeSlider.setValue(level, animated: false)
}
// Sound the alarm
let player = try AVAudioPlayer(contentsOf: audioUrl)
DispatchQueue.main.asyncAfter(deadline: .now() + player.duration) {
// Capture the AVPlayer instance in this closure to ensure is remains in scope until playback finishes
_ = player
if (setVolume) {
// After the duration of the audio, turn set the volume back to the previous level
volumeSlider.setValue(origVolume, animated: false)
}
}
player.play()
} catch {
print(error)
}
}
}
Remember: with loud volume comes loud user reactions, so use this sparingly!
