Question

I am trying to do something similar to what was requested in this question:
Playing audio with controls in iOS

I am using Storyboards with XCode 4.2. On my initial view page, I just have buttons that call other views, and no sounds are played there. These other views contain a UINavigationController with a BarButtonItem to allow you to go back. Other view pages will have buttons that allow one to play a sound. Each sound has its own play button, and there are resume, pause and stop buttons.

All sounds play fine, but if I hit the back button to the main page, the sound keeps playing. The desired behavior is for the sound to stop when navigating back to the main page via the back button.

Before storyboards, I could easily code a back button to stop the audio, but storyboards appear not that simple. It appears that I have to implement the method prepareForSegue. Okay, I can set the Segue identifier can be set in the Attributes Inspector, and referring back to the earlier post, I will use showPlayer.

But I was thinking I could code the prepareForSegue in one of my sound views, as seen in this cool example:
http://www.scott-sherwood.com/?p=219

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{

if([[segue identifier] isEqualToString:@"showPlayer"]){
     SoundPageController *theAudio = (SoundPageController *)[segue ViewController];
     theAudio.delegate = self;
 }
 }

In the main page ViewController.m, I tried adding:

  @property (strong, nonatomic) AVAudioPlayer *theAudio;

And I tried adding something like:

  - (void)viewDidLoad {
[super viewDidLoad];

// this is the important part: if we already have something playing, stop it!
if (audioPlayer != nil)
{
    [audioPlayer stop];
}
// everything else should happen as normal.
audioPlayer = [[AVAudioPlayer alloc]
           initWithContentsOfURL:url
           error:&error];

[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:nil];
[[AVAudioSession sharedInstance] setActive: YES error: nil];

I wasn’t able to get this to work, so I reverted the changes back to original. I will put my simplified code below, and if you have suggestions how to do it right, please let me know!

ViewController.h:

@interface ViewController : UIViewController {      
}

ViewController.m (pretty much default):

    #import "ViewController.h"

#import "AppDelegate.h"

@implementation ViewController

- (void)viewDidLoad
{

[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}

- (void)viewDidUnload
{

[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;

}

SoundPage1.h:
#import

#import <AVFoundation/AVAudioPlayer.h>

@interface occupy : UIViewController <AVAudioPlayerDelegate> {
AVAudioPlayer* theAudio;
}

//-(IBAction)PressBack:(id)sender; now the back button is linked up through storyboard
-(IBAction)pushButton1;
-(IBAction)pushButton2;
-(IBAction)play;
-(IBAction)stop;
-(IBAction)pause;
@end

SoundPage1.m

#import "SoundPage1.h"
#import "AppDelegate.h"
#import "ViewController.h"

@implementation SoundPage1

-(IBAction)pushButton {

NSString *path = [[NSBundle mainBundle] pathForResource:@"sound1" ofType:@"mp3"];
if(theAudio)[theAudio release];
theAudio = [[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath:path]    error:NULL];
theAudio.delegate = self;
theAudio.volume = 1.0;
[theAudio play];
 }

-(IBAction)pushButton2 {
NSString *path = [[NSBundle mainBundle] pathForResource:@"sound2" ofType:@"mp3"];
if(theAudio)[theAudio release];
theAudio = [[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath:path] error:NULL];
theAudio.delegate = self;
theAudio.volume = 1.0;
[theAudio play];
}

// Old code from XCode 3.x when creating a back button that could stop the audio was easy
//-(IBAction)PressBack:(id)sender{
//  [theAudio stop];
//  ViewController* myappname = [[ViewController alloc] initWithNibName:@"ViewController" bundle:nil];  
//  [self.navigationController pushViewController:myappname animated:NO];
//  }


- (void)viewDidLoad
{
[super viewDidLoad];
}

- (void)viewDidUnload
{
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}

Add in the code for play, stop and pause for the buttons.

I tried to format this, sorry in advance if it is hard to read.

Thanks for any suggestions!
Rob

Answer 1

You should stop the AVAudioPlayer in viewWillDisappear.

- (void)viewWillDisappear:(BOOL)animated { 
    [super viewWillDisappear:animated]; 
    if(theAudio && theAudio.isPlaying) {
        [theAudio stop]; 
    }
}