Choose a file randomly from Resources folder in iOS - iphone

Question

I have one thousand .mp3 files in my Resources folder within an iOS 4.2 XCode project.
For now I can select one file from the folder ( and play it ) with the following code in my .m file: ( Given the file name of "AFile.mp3" )
-(IBAction)playSound {
NSString *path = [[NSBundle mainBundle] pathForResource:#"AFile"ofType:#"mp3"];
AVAudioPLayer* theAudio =[[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath:path] error:NULL];
theAudio.delegate = self;
[theAudio play];
}
I'd like to be able to have the code choose an .mp3 randomly, play it, then select another file and play them all until they have all been played at least once. I assume I will need to use an NSArray, but am uncertain on how to proceeed.
I changed the code to the following, and am not getting any errors when I run this in the iOS Simulator. No File appears to be played when I run it though? When I launch the app, it quits, but does not log any errors in the Debugger..
Updated code:
-(IBAction)playSound {
NSArray *array = [[NSBundle mainBundle] pathsForResourcesOfType:#".mp3" inDirectory:#"Resources"];
NSString *randomPath = [array objectAtIndex:arc4random() % [array count]];
AVAudioPlayer* theAudio =[[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath: randomPath] error: NULL;
theAudio.delegate = self;
[theAudio play];
}
How can an I set up a simple array of the 1000 .mp3 files, and have the method play one at random?

Answer 1

AVAudioPlayer* theAudio=[[AVAudioPlayer alloc]initWithContentsofURL: [NSURL arrayURLWithPath:array] error:NULL];
should be:
AVAudioPlayer* theAudio=[[AVAudioPlayer alloc]initWithContentsofURL: [NSURL URLWithString:[array objectAtIndex:11]] error:NULL];
therefore the number '11' is a random file path. To get randomness you can use this:
int randomNumber = random()%1000; // random number between 0 and 1000
and then use randomNumber instead of 11
To play each file only one time you can play let's say song number four one time and then remove this item from your array. The next time you generate a random number use 999 instead of 1000 and so on till it gets to 1.
//EDIT: try following:
-(IBAction)playSound {
NSArray *array = [[NSBundle mainBundle] pathsForResourcesOfType:#".mp3" inDirectory:#"Resources"];
int rndm = arc4random() % [array count];
if (rndm<0) rndm*=-1;
NSString *randomPath = [array objectAtIndex:rndm];
AVAudioPlayer* theAudio =[[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath: randomPath] error: NULL;
theAudio.delegate = self;
[theAudio play];
}

Answer 2

Use this snippet. from a previous SO answer
NSString *bundleRoot = [[NSBundle mainBundle] bundlePath];
NSArray *dirContents = [[NSFileManager defaultManager] directoryContentsAtPath:bundleRoot];
NSArray *onlyJPGs = [dirContents filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:#"self ENDSWITH '.jpg'"]];
then get the array count.. and use random to get the random integer number and file.

Answer 3

Ok after looking into the apple documents here is the error. Somehow the even if we specify a custom directory it seems to be only for reference. The other mistake that I have found is that we only need to specify the extension without the "."
NSArray *audioPathArray = [[NSBundle mainBundle] pathsForResourcesOfType:#"mp3" inDirectory:nil];
NSLog(#"%d",[audioPathArray count]);
NSString *path = [audioPathArray objectAtIndex:arc4random() % [audioPathArray count]];
NSURL *randomPath = [[NSURL alloc]initFileURLWithPath:path];
AVAudioPlayer *theAudio = [[AVAudioPlayer alloc] initWithContentsOfURL:randomPath error:NULL];
[theAudio play];
This is what worked for me. Hope it helps you out.

Answer 4

Well, if you already have a reference to the array on which you would like to retrieve a random element from, then it's dead simple:
NSString *randomPath = [array objectAtIndex:arc4random_uniform([array count])];
Also, arc4random() is much better than rand()

Answer 5

Got it working on my project
When you import the Resources folder to your project select "Create folder references for any added folders". This will actually maintain the directory structure in your [NSBundle mainBundle].
You can then pull the contents like so:
NSString * bundlePath = [NSBundle mainBundle] bundlePath];
NSString * resourceFolderPath = [NSString stringWithFormat:#"%#/Resources", bundlePath];
NSArray * resourceFiles = [[NSFileManager defaultManager] directoryContentsAtPath:resourceFolderPath error:nil];
resourceFiles should contain a list of the contents of your Resources directory.
NSInteger randomFileIndex = arc4random() % [resourceFiles count];
NSString * randomFile = [resourceFiles objectAtIndex:randomFileIndex];