How to change track position on lock screen/control center?

Question

When playing a song with the ios 7 music app the user can use slider to change song position in the lock screen/the control center. Slider is active:

Answer 1

I was looking for the same thing but I don't think this is possible see this post:

How to enable audio scrubber in iOS Lock Screen control panel?

Also popular apps like Spotify and Soundcloud don't have this implemented.

If you are looking for a way to show the current music on the lock screen you need to do the following.

First when you play a new track update the NowPlayingInfo :

NSMutableDictionary *songInfo = [[NSMutableDictionary alloc] init];

    [songInfo setObject:trackTitle forKey:MPMediaItemPropertyTitle];
    [songInfo setObject:artistName forKey:MPMediaItemPropertyArtist];
    [songInfo setObject:duration forKey:MPMediaItemPropertyPlaybackDuration];
    [songInfo setObject:releaseDate forKey:MPMediaItemPropertyReleaseDate];
    [songInfo setValue:playbackRate forKey:MPNowPlayingInfoPropertyPlaybackRate];
    [songInfo setObject:elapsedTime forKey:MPNowPlayingInfoPropertyElapsedPlaybackTime];
    [songInfo setObject:albumArtImage forKey:MPMediaItemPropertyArtwork];
    [[MPNowPlayingInfoCenter defaultCenter] setNowPlayingInfo:songInfo];

To handle events from the Lockscreen, you first need to tell your app to start receiving events from the remote control. I do this in the application didFinishLaunchingWithOptions of my AppDelegate using the following code

 // Turn on remote control event delivery
[[UIApplication sharedApplication] beginReceivingRemoteControlEvents];

Next you need to implement remoteControlReceivedWithEvent method to handle the captured events. In APPDelegate add the following method

- (void)remoteControlReceivedWithEvent:(UIEvent *)receivedEvent {

 if (receivedEvent.type == UIEventTypeRemoteControl) {

    switch (receivedEvent.subtype) {
        case UIEventSubtypeRemoteControlPause:
            //pause code here
            break;

        case UIEventSubtypeRemoteControlPlay:
             //play code here
            break;

        case UIEventSubtypeRemoteControlPreviousTrack:
            // previous track code here
            break;

        case UIEventSubtypeRemoteControlNextTrack:
            //next track code here
            break;

        default:
            break;
    }
 }

}

More info on MPNowPlayingInfoCenter from the apple docs -> https://developer.apple.com/library/ios/documentation/mediaplayer/reference/MPNowPlayingInfoCenter_Class