How to play iOS built-in Sounds in your App

ShowNote presents an object with effects, including a sound effect.

UISounds

I utilized a device built-in sound file for this effect, and, naturally, the sound files are located in the UISounds directory:

let soundsRoot = URL(fileURLWithPath: "/System/Library/Audio/UISounds")

To list sounds, I retrieved all files from UISounds using contentsOfDirectory. Here are the details from the article:

let files = try! FileManager.default
    .contentsOfDirectory(at: soundsRoot,
                         includingPropertiesForKeys: nil,
                         options: [.skipsSubdirectoryDescendants,
                            .skipsPackageDescendants,
                            .skipsHiddenFiles])

However, my example app encountered an error stating,

Upon investigation, I observed the contents of /System/Library/Audio instead of UISounds.

There is no UISounds directory. So, I checked the path on my Macbook, and I saw a list exactly the same as in the simulator. Yes, when I accessed the root path from the Simulator, the Macbook’s root path was returned instead of the Simulator’s. This is because the Simulator doesn’t have its own disk.

Real Device

Therefore, I ran the example on my iPhone, and I could see the sound files.

Play

To play an audio file, we need a player. In this case, I used AVAudioPlayer, which is part of AVFoundation. So, you should import it first.

import AVFoundation

var player: AVAudioPlayer?

Usage is very easy. Initialize it with the URL of the sound file and play it.

player = try .init(contentsOf: selectedSound)
player?.play()

If you try to initialize the player with a directory, it will raise an error. To exclude directories, I used an extension to determine if the URL is a directory.

extension URL{
    func isDirectory() -> Bool{
        var is_dir : ObjCBool = ObjCBool.init(false);
        FileManager.default.fileExists(atPath: self.path, isDirectory: &is_dir);
        
        return is_dir.boolValue;
    }
}

And I filtered the children of UISounds.

let files = ...filter{ !$0.isDirectory }

The full source is in this example repository.

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Troubleshootings

The file “UISounds” couldn’t be opened because there is no such file.

Run in Real Device.

References

https://www.theiphonewiki.com/wiki//System/Library/Audio/UISounds

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