ios - 如何让程序在后台运行？

Question

我有一个程序可以录制当前正在播放的歌曲，但我希望该应用程序在后台运行，因此当用户在其他应用程序中或设备被锁定且我的应用程序处于后台时，他们去下一首歌，程序会知道。目前，我可以获取当前正在播放的歌曲，并在应用程序打开时将其放入解析中。

     func applicationDidEnterBackground(application: UIApplication) {
    print("entered background")
    NSNotificationCenter.defaultCenter().addObserver(self, selector: "getNowPlayingItem", name: MPMusicPlayerControllerNowPlayingItemDidChangeNotification, object: nil)
    musicPlayer.beginGeneratingPlaybackNotifications()
}

func getNowPlayingItem() {
    if  let nowPlaying = musicPlayer.nowPlayingItem  {
        let title = nowPlaying[MPMediaItemPropertyTitle] as? String
        let artisttest = nowPlaying[MPMediaItemPropertyTitle]
        if let artist = nowPlaying[MPMediaItemPropertyArtist] as? String{

            let objectPointer = PFObject(className: "Pointer")
            let object = PFObject(className: "MasterSongs")

            //    print("Artist: " + artist)


            let query = PFQuery(className: "Pointer")
            query.findObjectsInBackgroundWithBlock({
                (objects: [AnyObject]?, error: NSError?) -> Void in
                var objectIDs = objects as! [PFObject]

                for i in 0...objectIDs.count-1{
                    self.Parsearray.append((objectIDs[i].valueForKey("title") as? String)!)

                    // print(self.Parsearray)
                }


                if self.Parsearray.contains(title!){
                    print("already in db")
                }else{
                    objectPointer["title"] = title
                    objectPointer["user"] = PFUser.currentUser()
                    objectPointer["artist"] = artist
                    objectPointer.saveInBackground()


                }

            })




        }else{
            let object = PFObject(className: "MasterSongs")
            object.setObject(title!, forKey: "title")
            //object.setObject(artist!, forKey: "artist")
            object.saveInBackground()

            let objectPointer = PFObject(className: "Pointer")


            let query = PFQuery(className: "Pointer")
            query.findObjectsInBackgroundWithBlock({
                (objects: [AnyObject]?, error: NSError?) -> Void in
                var objectIDs = objects as! [PFObject]

                for i in 0...objectIDs.count-1{
                    self.Parsearray.append((objectIDs[i].valueForKey("title") as? String)!)

                    // print(self.Parsearray)
                }


                if self.Parsearray.contains(title!){
                    print("already in db")
                }else{
                    objectPointer["title"] = title
                    objectPointer["user"] = PFUser.currentUser()
                    objectPointer["artist"] = "No artist found :("
                    objectPointer.saveInBackground()


                }

            })





        }


    }


}

Answer 1

Apple 支持一些后台模式。如果您使用任何 Apple 框架进行音频播放，请选择您的 App 目标并进入 Capabilites 选项并启用后台模式并选择适当的选项。

检查屏幕截图。