如何讓程序在後臺運行？

Question

我有一個程序會記錄當前正在播放的歌曲，但我希望應用程序在後臺運行，所以當用戶在不同的應用程序中或設備被鎖定時，我的應用程序在後臺，到下一首歌，節目就會知道。目前，我可以將當​​前正在播放的歌曲放到應用程序打開時進行解析。

 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支持一些背景模式。如果您使用任何Apple音頻播放框架，請選擇您的應用程序目標並進入Capabilites選項並啓用後臺模式並選擇適當的選項。

檢查截圖。