Question

I have a url that is a link to an audio file and will be played using AVFoundation.framework. But for some reason, when the app reaches setting the NSData it crashes. Please help.

NSURL *url = [NSURL URLWithString:songPathForm];
NSData *soundData = [NSData dataWithContentsOfURL:url];

EDIT::::
This is what I did to make it stop crashing, but the data contains nothing

 NSString *url = [songPathForm stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];


                    //NSURL *url = [NSURL URLWithString:songPathForm];
                    NSURLRequest *songRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:url]
                                                              cachePolicy:NSURLRequestReloadIgnoringLocalCacheData timeoutInterval:60.0];

                NSURLConnection *songConnection = [[NSURLConnection alloc] initWithRequest:songRequest delegate:self];

                if(songConnection)
                {
                    songData = [[NSMutableData data] retain];
                }

It comes out as <>

Answer 1

There is absolutely no way to answer this question as it is worded, but here are some clues:

• if there is a crash, there is a backtrace. Post it.

• if there is a crash, there is some kind of an error. Post it.

Given that code, there are two failure modes that I can think of:

• songPathForm is nil or corrupt and/or not an URL.

• the data at the URL is too large to download and causes the app to attempt to allocate a HUGE amount of memory (there are cases where an allocation can be large enough to crash an app w/o the system jetsam mechanism kicking in).

There is no crash message, it just freezes and stops responding. url
is not nil it is…

Then why did you say your app crashed?!

dataWithContentsOfURL: is synchronously downloading the contents of whatever is at the URL.

Thus, you are blocking the main event loop during the download and that is why your app is not responsive.

You need to asynchronously download the data; i.e. not block the main event loop.

However that probably won’t entirely fix your problem as it looks like the contents of that URL is really large and, thus, you are likely going to run out of memory if you try to download in memory.

You either need to download the file to the disk or you need to download only parts of it that you need right now or you need to stream it (if it really is a large audio file as the URL implies).

---

The code in your updated question doesn’t make any sense. How do you expect songData to be filled with data from the connection?

When doing stuff asynchronously, you are basically saying “go do this stuff and let me know every now and then how it is going”. In this case, that’d be a notification that more data is available or that the connection is done reading (or in error).

You can’t ask for the data immediately because the data isn’t immediately available.

You’ll want to read through this guide.