iphone - Getting video from ALAsset

Question

Using the new asset library framework available in iOS 4 i see that I can get the url for a given video using the UIImagePickerControllerReferenceURL. The url returned is in the following format:

assets-library://asset/asset.M4V?id=1000000004&ext=M4V

I am trying to upload this video to a website so as a quick proof of concept I am trying the following

NSData *data = [NSData dataWithContentsOfURL:videourl];
[data writeToFile:tmpfile atomically:NO];

Data is never initialized in this case. Has anyone managed to access the url directly via the new assets library? Thanks for your help.

Answer 1

I use the following category on ALAsset:

static const NSUInteger BufferSize = 1024*1024;

@implementation ALAsset (Export)

- (BOOL) exportDataToURL: (NSURL*) fileURL error: (NSError**) error
{
    [[NSFileManager defaultManager] createFileAtPath:[fileURL path] contents:nil attributes:nil];
    NSFileHandle *handle = [NSFileHandle fileHandleForWritingToURL:fileURL error:error];
    if (!handle) {
        return NO;
    }

    ALAssetRepresentation *rep = [self defaultRepresentation];
    uint8_t *buffer = calloc(BufferSize, sizeof(*buffer));
    NSUInteger offset = 0, bytesRead = 0;

    do {
        @try {
            bytesRead = [rep getBytes:buffer fromOffset:offset length:BufferSize error:error];
            [handle writeData:[NSData dataWithBytesNoCopy:buffer length:bytesRead freeWhenDone:NO]];
            offset += bytesRead;
        } @catch (NSException *exception) {
            free(buffer);
            return NO;
        }
    } while (bytesRead > 0);

    free(buffer);
    return YES;
}

@end