iOS: Control AudioPlayer of another View(controller)

Question

I am programming a Quiz-App. In the Menu-ViewController I added Music to the project. The musicPlayer is running well and as long as the Menu-ViewController is in front, I can also controle it (play, pause, stop, ect.). When I display another ViewController, the Music runs in the Background, like I'd like to. But if try to call the play/pause Method of the first ViewController being in the secondViewController, the music nether paused nor stoped. I don't know why! If I add other Instructions to this Method, everything's going fine. (I tried the exit(0); Method. Here is my Code:

Controller 1 .h :

@implementation MenuViewController : <....> {
... }
@property (retain) AVAudioPlayer *backgroundPlayer;
- (void) playPauseMethod;

Controller 1 .m :

@interface ...
@end
@implementation MenuViewController 
@ synthesize 
- (void) soundChanger {
if (hintergrundPlayer.isPlaying) {
    [backgroundPlayer pause];}
else if (!backgroundPlayer.isPlaying) {
    [backgroundPlayer play];}}

Controller 2 .h :

#import "MenuViewController.h"
@interface QuizViewController : UIViewController{}

Controller 2 .m :

@interface ...
@end
@implementation MenuViewController 
@ synthesize ...
//..... musicPlayer is playing music.
- (IBAction)myMusic:(id)sender {
//first try:
[[[MenuViewController alloc] init].backgroundPlayer pause];
//second try:
[[[MenuViewController alloc] init] soundChanger];}

I'd like to control the music in every ViewController. I'm looking forward to your help.

Answer 1

You're creating a completely new MenuViewController in Controller2 with

[[MenuViewController alloc] init]

The best way to handle it would be to set up a protocol in controller 2 with something like

@protocol <Controller2Delegate>
-(void) playButtonPressed:(id)self;
@end

Then set up a delegate property (still in controller 2) like this:

@property (weak) id <Controller2Delegate> delegate;

Then, back in Controller 1, when you create the Controller 2, set it's delegate property, like this:

QuizViewController *controller2 = [[QuizViewController alloc] init]];
controller2.delegate = self;

And then create the playButtonPressed method somewhere in controller 1. From Controller 2, you'll do something like:

[self.delegate playButtonPressed:self];

And that will call the method in Controller 1, where you can pause the background player.