近期准备将项目转化为OC与swift混合开发。试着写一个swift音乐播放器的demo，体会到了swift相对OC的优势所在。废话不多说。先上效果图：

ps:身为杰伦的铁粉。demo的主题必须跟杰伦有关，哈哈！并且自我感觉我有转型UI的天赋，有木有？

一、导入OC文件
创建好swift项目之后，导入OC工具类文件，Xcode会自己主动生成桥接文件

打开这个文件，在开头导入OC工具类的头文件，就能够调用OC工具类了

//
//  Use this file to import your target's public headers that you would like to expose to Swift.
//
#import "UIView+Frame.h"

二、界面绘制
这里方便起见，没有考虑性能问题。仅仅是简单的demo。所以直接创建十个音乐button。加上一个播放button和一个暂停button。十个乐曲button放在一个UIScrollView上面。并且播放的音乐是本地音乐，首先在viewDidLoad前创建全局变量。代码例如以下：

    var btnIndex = 0let arrMusicName = ["蒲公英的约定","窃爱","退后","告白气球","阳光宅男","甜甜的","彩虹","心雨","哪里都是你","说好的幸福呢"]let btnPlay:UIButton = UIButton(type:.System)let btnPause:UIButton = UIButton(type:.System)override func viewDidLoad() {

界面绘制代码例如以下：

let SCREEN_W = UIScreen.mainScreen().bounds.size.widthlet SCREEN_H = UIScreen.mainScreen().bounds.size.heightlet ivBack:UIImageView = UIImageView(frame:CGRect(x:0, y:20, width:SCREEN_W, height:SCREEN_H))ivBack.image = UIImage(named:"aa.jpg")self.view.addSubview(ivBack)let lbTitle:UILabel = UILabel(frame:CGRect(x:0, y:20, width:SCREEN_W, height:44))lbTitle.text = "LXY的杰伦情歌"lbTitle.textColor = UIColor.whiteColor()lbTitle.textAlignment = NSTextAlignment.CenterlbTitle.backgroundColor = UIColor.blackColor()lbTitle.alpha = 0.2self.view.addSubview(lbTitle)let scv:UIScrollView = UIScrollView(frame:CGRect(x:0, y:64, width:SCREEN_W, height:SCREEN_H - 74 - 44))scv.backgroundColor = UIColor.clearColor()self.view.addSubview(scv)var boom:Int = 0for st in arrMusicName {print(st)if let index = arrMusicName.indexOf(st) {let btn:UIButton = UIButton(type:.System)btn.backgroundColor = UIColor.whiteColor()btn.alpha = 0.5btn.setTitle(st, forState: UIControlState.Normal)btn.setTitleColor(UIColor.blackColor(), forState: UIControlState.Normal)btn.titleLabel?.font = UIFont.systemFontOfSize(16)btn.layer.masksToBounds = truebtn.layer.shadowOffset = CGSizeMake(0, 10)btn.layer.shadowColor = UIColor.grayColor().CGColorbtn.layer.shadowOpacity = 1btn.layer.shadowRadius = 10btn.layer.cornerRadius = 6btn.tag = index//传递触摸对象（即点击的button），须要在定义action參数时，方法名称后面带上冒号btn.addTarget(self, action:#selector(play(_:)), forControlEvents:.TouchUpInside)if index%2 == 0 {btn.frame = CGRectMake(SCREEN_W/9,  20 + (SCREEN_W/3 + SCREEN_W/9)*CGFloat(index/2),SCREEN_W/3,SCREEN_W/3)}else {btn.frame = CGRectMake(5*SCREEN_W/9,  20 + (SCREEN_W/3 + SCREEN_W/9)*CGFloat(index/2),SCREEN_W/3,SCREEN_W/3)}scv.addSubview(btn)boom = Int(btn.bottom)}}scv.contentSize = CGSizeMake(SCREEN_W,CGFloat(boom + 20))btnPlay.frame = CGRectMake(0, scv.bottom, SCREEN_W/2 - 10, 44)btnPlay.backgroundColor = UIColor.whiteColor()btnPlay.alpha = 0.5btnPlay.setTitle("播放", forState: UIControlState.Normal)btnPlay.setTitleColor(UIColor.blueColor(), forState: UIControlState.Normal)btnPlay.titleLabel?

.font = UIFont.systemFontOfSize(16) btnPlay.addTarget(self, action:#selector(MPMediaPlayback.play), forControlEvents:.TouchUpInside) btnPlay.hidden = true self.view.addSubview(btnPlay) btnPause.frame = CGRectMake(10 + SCREEN_W/2, scv.bottom, SCREEN_W/2 - 10, 44) btnPause.backgroundColor = UIColor.whiteColor() btnPause.alpha = 0.5 btnPause.setTitle("暂停", forState: UIControlState.Normal) btnPause.setTitleColor(UIColor.blueColor(), forState: UIControlState.Normal) btnPause.titleLabel?.font = UIFont.systemFontOfSize(16) btnPause.addTarget(self, action:#selector(MPMediaPlayback.pause), forControlEvents:.TouchUpInside) btnPause.hidden = true self.view.addSubview(btnPause) } func play(btn: UIButton){ btnIndex = btn.tag let music = arrMusicName[btn.tag] let path = NSBundle.mainBundle().pathForResource(music, ofType: "mp3") let pathURL=NSURL(fileURLWithPath: path!) do { audioPlayer = try AVAudioPlayer(contentsOfURL: pathURL) } catch { audioPlayer = nil } audioPlayer?.prepareToPlay() audioPlayer.play() btnPause.hidden = false btnPlay.hidden = false

三、音乐播放器创建

class AudioManager: NSObject, AVAudioPlayerDelegate {static let sharedManager = AudioManager()  // singletonvar audioPlayer: AVAudioPlayer!
}

然后在曲剧变量里实例化播放器

var audioPlayer = AudioManager.sharedManager.audioPlayer

四、button事件绑定

1、音乐button播放音乐事件

 func playWitnIndex(index: Int){let music = arrMusicName[index]let path = NSBundle.mainBundle().pathForResource(music, ofType: "mp3")let pathURL=NSURL(fileURLWithPath: path!)do {audioPlayer = try AVAudioPlayer(contentsOfURL: pathURL)} catch {audioPlayer = nil}audioPlayer?.prepareToPlay()audioPlayer.play()btnPause.hidden = falsebtnPlay.hidden = false}

这种方法吧button带过来。通过button的tag值推断所点击的button

2、播放button的点击事件

func play(){audioPlayer.play()}

3、暂停button的点击事件

 func pause(){audioPlayer.pause()}

到这里。音乐播放器的基本功能就已经实现了，点击就会有音乐播放了。并且播放暂停功能都已经实现

五、音乐后台播放的实现

要实现后台音乐播放功能，还学要对音乐播放器设置一下

在viewDidLoad方法中加入一下代码：

UIApplication.sharedApplication().beginReceivingRemoteControlEvents()do {try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayAndRecord)try AVAudioSession.sharedInstance().setActive(true)} catch {}

仅仅加入这个还不够，须要对project进行设置
在info.plist加入Required background modes，详细如图：

这样，音乐播放器就实现了后台播放功能

六、音乐播放器锁屏音乐播放设置

加入setLockView方法，代码例如以下：

func setLockView(){MPNowPlayingInfoCenter.defaultCenter().nowPlayingInfo = [// 歌曲名称MPMediaItemPropertyTitle:arrMusicName[btnIndex],// 演唱者MPMediaItemPropertyArtist:"周杰伦",// 锁屏图片MPMediaItemPropertyArtwork:MPMediaItemArtwork(image: UIImage(named: "aa.jpg")!),//MPNowPlayingInfoPropertyPlaybackRate:1.0,// 总时长            MPMediaItemPropertyPlaybackDuration:audioPlayer.duration,// 当前时间        MPNowPlayingInfoPropertyElapsedPlaybackTime:audioPlayer.currentTime]}

在viewDidLoad方法中调用这种方法:

  self.setLockView()

这样就实现了锁屏界面了button设置

锁屏button点击事件实现须要重写remoteControlReceivedWithEvent方法，代码例如以下：

override func remoteControlReceivedWithEvent(event: UIEvent?) {switch event!.subtype {case .RemoteControlPlay:  // playbuttonaudioPlayer.play()case .RemoteControlPause:  // pausebuttonaudioPlayer.pause()case .RemoteControlNextTrack:  // next// ▶▶self.btnIndex = self.btnIndex + 1self.playWitnIndex(self.btnIndex)self.setLockView()breakcase .RemoteControlPreviousTrack:  // previous// ◀◀if self.btnIndex>0 {self.btnIndex = self.btnIndex - 1self.playWitnIndex(self.btnIndex)self.setLockView()}breakdefault:break}}

七、外放问题的解决

此时。尽管功能都实现了，可是会发现音乐播放声音特别小，由于AVAudioPlayer默认是听筒播放，而不是扬声器播放
这里须要在播放器设置里加入例如以下设置代码

 let session = AVAudioSession.sharedInstance()try session.setCategory(AVAudioSessionCategoryPlayAndRecord, withOptions: AVAudioSessionCategoryOptions.DefaultToSpeaker)

其它设置如图所看到的：

到这里。这个swift版的lxy杰伦情歌APP就大功告成了，文章最后附上项目源代码(由于音乐文件太大，仅仅保留前两首歌曲)，希望大家喜欢：

项目源代码下载地址