If you would like to try my code, you have to prepare music files. (does not matter what type of extension, but highly recommend mp3 or mp4)

Development Environment

OS X El Captain 10.11.2
Xcode Version 8.0

Language

Swift 3.0

Step

1- Add your music file to Assets.xcassets

2- import AVFoundation to activate the library to use

import AVFoundation

3- Declare a parameter of AVAudioPlayer

var player: AVAudioPlayer?

4- Create main function that will play a music file in Xcode

 func playSound() {
        guard let sound = NSDataAsset(name: "前前前世") else {
            print("The music file that you mentioned is not found in asset folder")
            return
        }
        do {
            try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
            try AVAudioSession.sharedInstance().setActive(true)
            player = try AVAudioPlayer(data: sound.data, fileTypeHint: AVFileTypeMPEGLayer3)
            player!.play()
        } catch let error as NSError {
            print("Error: \(error.localizedDescription)")
        }
    }

5- Done

Source Code

ViewController.swift

import UIKit
import AVFoundation

class ViewController: UIViewController {
   
    var player: AVAudioPlayer?

    override func viewDidLoad() {
        super.viewDidLoad()
        playSound()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}

/* Function */
extension ViewController{
    func playSound() {
        guard let sound = NSDataAsset(name: "前前前世") else {
            print("The music file that you mentioned is not found in asset folder")
            return
        }
        do {
            try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
            try AVAudioSession.sharedInstance().setActive(true)
            player = try AVAudioPlayer(data: sound.data, fileTypeHint: AVFileTypeMPEGLayer3)
            // You can print name of music that you are gonna play.
            print (sound.name)
            player!.play()
        } catch let error as NSError {
            print("Error: \(error.localizedDescription)")
        }
    }
}

Conclusion

これで音楽再生アプリつくれちゃいますね！