Difficulty with accessing list of URLs in XML file - objective-c

Question

I am trying to make an app that plays MP3 songs. My program flow is like this:
I have an XML file here in my website: http://jeewanaryal.web44.net/SongsXML/songsListXML.xml. It has song titles and the actual URL of those songs on the Internet. I have the following code for my Pop songs section:
NSString *urlString = #"http://jeewanaryal.web44.net/SongsXML/songsListXML.xml";
NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:urlString]];
NSDictionary *dict = [XMLReader dictionaryForXMLData:data error:nil];
NSArray *arrayOfSongs = [[NSArray alloc] initWithArray:[[[dict objectForKey:#"list"] objectForKey:#"songs"] objectForKey:#"song"]];
StartStopSound = [UIButton buttonWithType:UIButtonTypeRoundedRect];
StartStopSound.frame = CGRectMake(60, 360, 200, 30);
[StartStopSound setTitle:#"बजाउनुहोस" forState:UIControlStateNormal];
[StartStopSound addTarget:self action:#selector(playSong) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:StartStopSound];
back = [UIButton buttonWithType:UIButtonTypeRoundedRect];
back.frame = CGRectMake(20, 320, 100, 30);
[back setTitle:#"पछाडीको गीत " forState:UIControlStateNormal];
[back addTarget:self action:#selector(playSong) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:back];
next = [UIButton buttonWithType:UIButtonTypeRoundedRect];
next.frame = CGRectMake(200, 320, 100, 30);
[next setTitle:#"अगाडीको गीत" forState:UIControlStateNormal];
[next addTarget:self action:#selector(playSong) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:next];
NSData *myData = [[NSData alloc] init ];
NSString *urlString1 = [[NSString alloc] init];
for (NSDictionary *fruitDict in arrayOfSongs) {
UILabel *songTitle = [[UILabel alloc] initWithFrame:CGRectMake(40, 200, 300, 40)];
songTitle.text = [NSString stringWithFormat:#"%#",[[fruitDict objectForKey:#"title"] objectForKey:#"text"]];
[self.view addSubview:songTitle];
urlString1 = [NSString stringWithFormat:#"%#",[[fruitDict objectForKey:#"url"] objectForKey:#"text"]];
//NSLog(#"\n\n -- URL STRING : %# \n\n",urlString);
}
myData = [NSData dataWithContentsOfURL:[NSURL URLWithString:urlString1]];
player = [[AVAudioPlayer alloc] initWithData:myData error:nil];
[player play];
[player numberOfLoops];
[player currentTime];
This works fine for a single song; that is, it only plays the last URL of my XML file. I want to make all songs to be played one by one, making a "Next" and "Previous" button on my app.
Will you please tell me how I can implement that? I am using XMLReader.h and XMLReader.m file to parse the data from XML into my app.

Answer 1

You would need to store arrayOfSongs somewhere in the class. The "back" and "next" buttons would need separate actions (e.g. playPreviousSong, playNextSong). These methods would then look something like this:
-(void) playPreviousSong
{
NSString *url = [[self songs] objectAtIndex:[self songIndex] - 1];
[self playSong:url];
[self setSongIndex:[self songIndex - 1];
}
This is a crude implementation just to show how it'd fit together. Basically you need to store the list of songs and keep track of which song is "selected"/playing, then just select the next/previous one.
Edit: To answer your question in the comments, you have already extracted the array of song URLs, you simply need to keep a reference to it in the class. E.g.
#interface AudioPlayer {
NSArray *_songs;
NSUInteger *_songIndex;
}
Then in the #implementation instead of creating a arrayOfSongs variable, simply reference the array from the instance variable:
_songs = [[NSArray alloc] initWithArray:[[[dict objectForKey:#"list"] objectForKey:#"songs"] objectForKey:#"song"]];
Then in, for example, the playPreviousSong method:
-(void) playPreviousSong
{
NSString *url = [_songs objectAtIndex:_songIndex - 1];
[self playSong:url];
_songIndex--;
}