How does Soundcloud app skip to next track so fast? - ios

Question

I'm building my first app and it's a Soundcloud client. Right now, everytime a track is selected to play, I have to go on and do a NSURLSessionDataTask fetch to get the binary data, but this takes a long time. And when I skip, to the next track, I have to add the logic in to download the next song ahead of time when the current song is playing...though, this is still slow if the user skips quickly:/
The Soundcloud native app skips instantly. How do it work? I've tried using Soundcloud iOS SDK but it is now deprecated.
Here is my song fetch:
-(void)fetchTrack: (SCTrack*)selectedTrack completionHandler: (void(^)(NSData *trackData, NSString *error)) completionHandler; {
NSString* clientID = #"41a5278fd8c704c3eb5a4a0ca38f9036";
NSString* streamURL = selectedTrack.stream_url;
NSString* urlString = [NSString stringWithFormat:#"%#?client_id=%#", streamURL, clientID];
NSURL* url = [[NSURL alloc]initWithString:urlString];
NSLog(#"%#", urlString);
NSMutableURLRequest* request = [[NSMutableURLRequest alloc]initWithURL:url];
request.HTTPMethod = #"GET";
NSURLSessionDataTask* dataTask = [[self session] dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
NSHTTPURLResponse* callResponse = (NSHTTPURLResponse*)response;
if ([callResponse isKindOfClass:[NSHTTPURLResponse class]]) {
NSInteger responseCode = [callResponse statusCode];
if (responseCode >= 200 && responseCode <= 299) {
NSData* trackData = data;
NSLog(#"STREAM 200");
[[NSOperationQueue mainQueue]addOperationWithBlock:^{
NSLog(#"%#", data);
completionHandler(trackData, nil);
}];
}else{
NSLog(#"%ld", (long)responseCode);
}
}
}];
[dataTask resume];
}
This is how I'm playing and attempting to fetch the next song while the current track is playing:
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
self.selectedTrack = self.SCTrackList[indexPath.row];
self.selectedTrackRow = indexPath.row;
[[SoundCloudAPI sharedInstance]fetchTrack:self.selectedTrack completionHandler:^(NSData *trackData, NSString *error) {
self.player = [[AVAudioPlayer alloc]initWithData: trackData error:nil];
[self.player prepareToPlay];
[self.player play];;
}];
[self prepareForNextTrack:self.selectedTrack];
}
-(void)prepareForNextTrack: (SCTrack*)trackPlaying {
self.selectedTrackRow += 1;
self.selectedTrack = self.SCTrackList[self.selectedTrackRow];
[[SoundCloudAPI sharedInstance]fetchTrack:self.selectedTrack completionHandler:^(NSData *trackData, NSString *error) {
self.trackDataToPlay = trackData;
}];
}
- (IBAction)nextPressed:(id)sender {
self.player = [[AVAudioPlayer alloc]initWithData: self.trackDataToPlay error:nil];
[self.player prepareToPlay];
[self.player play];;
[self prepareForNextTrack:self.selectedTrack];
}
Also, I'm new, so I'm sure my code is pretty clunky and would appreciated if anyone can point out ways to improve.
Thanks for pointing in the right direction!

Answer 1

So it turns I made things wayyyy more complicated than had to be. All I had to do was the dataWithContentsOfURL method to go retrieve the song passing in the token.
NSData *data =[NSData dataWithContentsOfURL:[NSURL URLWithString:[NSString stringWithFormat:#"%#?oauth_token=%#",self.selectedTrack.stream_url, self.token]]];
And of course, put the data in the AVAudioPlayer.
Basically, getting rid of my fetchTrack function above.