Most music players can be controlled by the Control Center of Apple or earphone.

1. Tell the app to begin receiving remote-control events.

add the code below into your AppDelegate.m file

    [[UIApplication sharedApplication] beginReceivingRemoteControlEvents]; 

2. Implementing the method 

- (void)remoteControlReceivedWithEvent:(nullable UIEvent *)event

in AppDelegate.m file too.

You have pay attention to event's two proterties, that are type and subtype.