NSString from NSData returns nil

Question

So I am using Parse (which is pretty sweet) and I'm in the process of downloading files (short video files - no more then 1mb) from the parse server to my application to play. Now the way it works is (via documentation)..

PFFile* videoFile = [[tempArray objectAtIndex:i] objectForKey:@"track"];


[videoFile getDataInBackgroundWithBlock:^(NSData *data, NSError *error) {
       if (!error) {
           NSString* dataString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
           NSURL* videoURL = [NSURL URLWithString:dataString];
           // now do something with this videoURL (i.e. play it!)
           [data writeToFile:@"trackFile" atomically:YES];
                NSURL *filePath = [NSURL fileURLWithPath:@"trackFile"];
                NSLog(@"File Path: %@",filePath);

                AVAsset* asset = [AVAsset assetWithURL:filePath];
                AVPlayerItem* playerItem = [[AVPlayerItem alloc] initWithAsset:asset];

       }
}

On download completion you are suppossed to create a string from the data and then a url from the string. Only problem is - the dataString always returns NULL/nil. I have confirmed that the data property is not empty and does in fact hold the video data. Why is this happening? Any help would be greatly appreciated. Thanks in advance!

Answer 1

Couple things that need to be determined first:

1. does the NSData object actually have any data, i.e., data.length > 0?
2. does the NSData object hold video data OR the url of the video data (not exactly clear)?

Making the assumption that the NSData object is holding the url and it's length is greater than 0, then you might want to try:

NSString* dataString = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];

Answer 2

I have confirmed that the data property is not empty and does in fact hold the video data.

Video data is not a UTF-8 string. It's definitely not a UTF-8 string representation of an URL. So when you say "interpret this video data as UTF-8," Cocoa rightly responds that it is not UTF-8 (because it's video data).

The simplest solution is to write this to disk, and then play the file.