Swift - How do I get the file path inside a folder

First make sure when you drag your folder audioFiles to your project to check copy items if needed and select create folder references. Make sure it shows a blue folder if your project.

Also NSBundle method pathForResource has an initialiser that you can specify in which directory your files are located:

let audioFileName = "audioName" 

if let audioFilePath = Bundle.main.path(forResource: audioFileName, ofType: "mp3", inDirectory: "audioFiles") {
    print(audioFilePath)
}

If you would like to get that file URL you can use NSBundle method URLForResource(withExtension:, subdirectory:)

if let audioFileURL = Bundle.main.url(forResource: audioFileName, withExtension: "mp3", subdirectory: "audioFiles") {
    print(audioFileURL)
}