ViewController

import UIKit
import AVFoundation

class ViewController: UIViewController, AVAudioPlayerDelegate {
    @IBOutlet weak var channelLabel: UILabel!
    @IBOutlet weak var artistLabel: UILabel!
    @IBOutlet weak var musicLabel: UILabel!
    
    @IBOutlet weak var playButton: UIButton!
    @IBOutlet weak var progressView: UIProgressView!
    
    var channelList: Array<ChannelModel>?
    var musicList: Array<MusicModel>?
    var currentIndex: Int = 0 //当前歌曲的位置
    var player: AVAudioPlayer?
    var timer: NSTimer?
    
    //下载数据
    func fetchData(url: NSURL?, completion: (NSData?) -> Void) {
        if let u = url {
            let task = NSURLSession.sharedSession().dataTaskWithURL(u, completionHandler: { (data, response, error) in
                if error == nil {
                    if let httpResponse = response as? NSHTTPURLResponse {
                        if httpResponse.statusCode == 200 {
                            //切换到主线程
                            dispatch_async(dispatch_get_main_queue()) {
                                completion(data)
                            }
                        }
                    }
                }
            })
            task.resume()
        }
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        //频道列表
        let url = NSURL(string: "https://gitshell.com/wcrane/FM-Res/raw/blob/master/channels.json")
        //下载频道列表
        fetchData(url) { (data) in
            if let d = data {
                let array = try! NSJSONSerialization.JSONObjectWithData(d, options: .AllowFragments) as? Array<NSDictionary>
                
                self.channelList = array!.map({ (dict: NSDictionary) -> ChannelModel in
                    return ChannelModel(dict: dict)
                })
                
                //频道列表下载完毕
                let c = self.channelList?.first
                self.loadChannelDetail(c!.channel_id)
            }
        }
    }

    //代码重构
    func loadChannelDetail(channelId: String) {
        let encodeId = channelId.stringByAddingPercentEncodingWithAllowedCharacters(NSCharacterSet.URLQueryAllowedCharacterSet())
        let path = "http://fm.baidu.com/dev/api/?tn=playlist&format=json&id=" + encodeId!
        let url = NSURL(string: path)
        
        fetchData(url) { (data) in
            if let d = data {
                let dict = try! NSJSONSerialization.JSONObjectWithData(d, options: .AllowFragments) as? NSDictionary
                let array = dict!["list"] as? Array<NSDictionary>
                
                self.musicList = array!.map({ (dict: NSDictionary) -> MusicModel in
                    return MusicModel(dict: dict)
                })
                
                //歌曲列表下载完成
                let m = self.musicList?.first
                print("歌曲Id：\(m?.songId)")
                self.loadMusicDetail(0)
            }
        }
    }
    
    //下载歌曲详情
    func loadMusicDetail(index: Int) {
        guard index >= 0 && index < musicList?.count else {
            return
        }
        
        currentIndex = index
        let music = self.musicList![index]
        let path = "http://music.baidu.com/data/music/fmlink?type=mp3&rate=320&songIds=\(music.songId)"
        let url = NSURL(string: path)
        fetchData(url) { (data) in
            if let d = data {
                let dict = try! NSJSONSerialization.JSONObjectWithData(d, options: .AllowFragments)
                let errorCode = dict["errorCode"] as? NSNumber
                if  errorCode!.integerValue == 22000 {
                    let songData = dict["data"]
                    let songList = songData!!["songList"] as? NSArray
                    let songDict = songList?.firstObject as? NSDictionary
                    
                    music.addInfo(songDict!)
                    
                    self.showMusicInfo(music)
                    self.downloadMusicFile(music)
                }
                else {
                    print("没有歌曲")
                    self.loadMusicDetail(index + 1)
                }
            }
        }
    }
    
    //下载歌曲文件
    func downloadMusicFile(music: MusicModel) {
        guard music.songLink != nil else {
            print("没有歌曲链接")
            return
        }
        
        fetchData(music.songLink) { (data) in
            if let d = data {
                self.playMusic(d)
            }
        }
    }
    
    //显示歌曲信息
    func showMusicInfo(music: MusicModel) {
        channelLabel.text = music.albumnName
        artistLabel.text = music.artistName
        musicLabel.text = music.songName
    }
    
    //播放
    func playMusic(music: NSData) {
        if player != nil && player!.playing {
            timer?.invalidate()
            player?.stop()
        }
        
        player = try! AVAudioPlayer(data: music)
        player?.delegate = self
        player?.prepareToPlay()
        player?.play()
        
        //在主线程中执行
        timer = NSTimer.scheduledTimerWithTimeInterval(0.1, target: self, selector: #selector(didTime(_:)), userInfo: nil, repeats: true)
        
        playButton.selected = true
    }
    
    func didTime(timer: NSTimer) {
        progressView.progress = Float(player!.currentTime / player!.duration)
        print(progressView.progress)
    }
    
    //切换频道
    @IBAction func didChannelClicked(sender: UIButton) {
    }

    //播放控制
    @IBAction func didPlayClicked(sender: UIButton) {
        if let p = player {
            if p.playing {
                p.pause()
            }
            else {
                p.play()
            }
            
            sender.selected = p.playing
        }
    }

    @IBAction func didBackClicked(sender: UIButton) {
        if currentIndex == 0 {
            currentIndex = musicList!.count - 1
        }
        
        loadMusicDetail(currentIndex - 1)
    }
    
    @IBAction func didForwardClicked(sender: UIButton) {
        if currentIndex == musicList!.count - 1 {
            currentIndex = 0
        }
        
        loadMusicDetail(currentIndex + 1)
    }
    
    func audioPlayerDidFinishPlaying(player: AVAudioPlayer, successfully flag: Bool) {
        timer?.invalidate()
        playButton.selected = false
        
        didForwardClicked(UIButton())
    }
}

ChannelModel

class ChannelModel {
    var channel_id: String!
    var channel_name: String!
    
    init(dict: NSDictionary) {
        if let id = dict["channel_id"] {
            channel_id = id as! String
        }
        
        if let chName = dict["channel_name"] {
            channel_name = chName as! String
        }
        
    }
    
}

MusicModel

class MusicModel: NSObject{
    var artistName: String!
    var songName: String!
    var albumnName: String!
    var songLink: NSURL!
    var songId: Int!
    
    init(dict: NSDictionary){
        if let id = dict["id"] as? NSNumber{
            songId = id.integerValue
        }
    }
    func addinfo(dict: NSDictionary){
        if let aName = dict["artistName"]{
            artistName = aName as! String
        }
        if let sName = dict["songName"]{
            songName = sName as! String
        }
        if let aName = dict["albumName"] as? String {
            albumnName = aName
        }
        if let sLink = dict["songLink"]{
            songLink = NSURL(string: sLink as! String)
        }
    }
}