How to convert NSUrl to NSString?

Question

After AVAssetExportSession has complete export video. I have plan to garb Video Path to upload via Youtube. but [GDataUtilities MIMETypeForFileAtPath:path def

Answer 1

Is it possible to convert NSUrl in to NSString for video file path.

Yes. Send it an absoluteString message.

i have try to use NSString *path = [ExportoutputURL absoluteString]; but it crash.

If you want a path, send the URL a path message. A string representing a URL is generally not a valid path; if you want a path, ask it for one.

As for the crash, it does not mean absoluteString is wrong. Sending absoluteString to an NSURL object is the correct way to get an NSString object that represents the URL. The problem is somewhere else.

Error EXC_BAD_ACCESS at

NSString *path = [ExportoutputURL absoluteString];

This probably means that ExportoutputURL points to something that is not nil but is also not a valid object. It might have pointed to an NSURL object at some point, but it doesn't now.

My guess would be that the problem is this:

ExportoutputURL = session.outputURL;

You assign the URL to the ExportoutputURL instance variable, but you don't retain the object or make your own copy. Therefore, you don't own this object, which means you are not keeping it alive. It may die at any time, most probably after this method (exportDidFinish:) returns.

The crash is because you call uploadVideoFile later, after the URL object has already died. You still have a pointer to it, but that object no longer exists, so sending a message to it—any message—causes a crash.

There are three simple solutions:

1. Retain the URL object when you assign it to your instance variable.
2. Make your own copy of the URL object and assign that to the instance variable.
3. Declare ExportoutputURL as a property, with either the strong keyword or the copy keyword, and assign the object to the property, not the instance variable. That will call the property's setter, which, if you synthesize it or implement it correctly, will retain or copy the URL for you.

Either way, you will own the object, and that will keep it alive until you release it. Accordingly, you will need to release it when you are done with it (in dealloc, if not earlier), so that you don't leak it.

This all assumes that you are not using ARC. If you are using Xcode 4.2 or later, and can require iOS 4 or later, you should migrate your project to ARC, as it makes so many things much simpler. You would not need to retain or copy this object if you were using ARC, which means that migrating to ARC now is a fourth solution (but certainly a larger-scale one).