Question

I have this app that has several view controllers. In the app delegate, I set it so that as soon as the app finishes launching, the background music starts. However, on another view controller, I have this button that plays this video. My problem is that when I play the movie, the background audio overlaps with the movie. My question is, how do I stop the music when I play the movie and play the music after the movie ends.
Here is my app_delegate.h:

#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>

@interface App_Delegate : NSObject <UIApplicationDelegate> {

    UIWindow *window;
    UINavigationController *navigationController;
}

@property (nonatomic, retain) IBOutlet UIWindow *window;
@property (nonatomic, retain) IBOutlet UINavigationController *navigationController;

@end

Here is my App_Delegate.m

#import "App_Delegate.h"
#import "RootViewController.h"


@implementation App_Delegate

@synthesize window;
@synthesize navigationController;


#pragma mark -
#pragma mark Application lifecycle

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    

    {NSString* soundFilePath = [[NSBundle mainBundle] pathForResource:@"beethoven_sym_5_i" ofType:@"mp3"];
        NSURL* soundFileURL = [NSURL fileURLWithPath:soundFilePath];
        AVAudioPlayer* player = [[AVAudioPlayer alloc] initWithContentsOfURL:soundFileURL error:nil];
        player.numberOfLoops=-1;
        [player play];
    }


    // Override point for customization after application launch.

    // Set the navigation controller as the window's root view controller and display.
    self.window.rootViewController = self.navigationController;
    [self.window makeKeyAndVisible];

    return YES;
}


- (void)dealloc {
    [navigationController release];
    [window release];
    [super dealloc];
}


@end

My MovieViewController.h:

#import <UIKit/UIKit.h>
#import <MediaPlayer/MediaPlayer.h>
#import <AVFoundation/AVFoundation.h>

@interface MovieViewController : UIViewController {

    IBOutlet UIScrollView *sesamescroller;
}

- (IBAction)playsesamemovie:(id)sender;


@end

Finally, my MovieViewController.m

#import "MovieViewController.h"


@interface MovieViewController ()

@end

@implementation MovieViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad


- (void)viewDidUnload


- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

- (IBAction)playsesamemovie:(id)sender {
    NSString *filepath   =   [[NSBundle mainBundle] pathForResource:@"How to make Sesame chicken" ofType:@"mp4"];
    NSURL    *fileURL    =   [NSURL fileURLWithPath:filepath];
    MPMoviePlayerController *moviePlayerController = [[MPMoviePlayerController alloc] initWithContentURL:fileURL];
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(moviePlaybackComplete:)
                                                 name:MPMoviePlayerPlaybackDidFinishNotification
                                               object:moviePlayerController];
    [self.view addSubview:moviePlayerController.view];
    moviePlayerController.fullscreen = YES;
    [moviePlayerController play];
}


- (void)moviePlaybackComplete:(NSNotification *)notification
{
    MPMoviePlayerController *moviePlayerController = [notification object];
    [[NSNotificationCenter defaultCenter] removeObserver:self
                                                    name:MPMoviePlayerPlaybackDidFinishNotification
                                                  object:moviePlayerController];
    [moviePlayerController.view removeFromSuperview];
    [moviePlayerController release];
}

- (void)dealloc {
    [sesamescroller release];
    [super dealloc];
}
@end

Answer 1

The code you show has a local variable pointing to the player object. To control the player, other code needs to be able to find it. Like this:

In App_Delegate.h:

@property (strong) AVAudioPlayer *player;

in App_Delegate.m: (where did this underbar come from? Most unconventional!)

self.player = [[AVAudioPlayer alloc] initWithContentsOfURL:soundFileURL error:nil];
self.player.numberOfLoops=-1;
[self.player play];

Then, wherever you want to control it:

[((App_Delegate *)([UIApplication sharedApplication].delegate)).player pause];
// ...
[((App_Delegate *)([UIApplication sharedApplication].delegate)).player play];