I wish to extract the image using ALAssetsLibrary and ALAsset directly in the form of a NSData object.
Using a NSURL I take out the image in the following manner.
ALAssetsLibrary *assetLibrary=[[ALAssetsLibrary alloc] init];
[assetLibrary assetForURL:[[self.imagedata objectAtIndex:i] resultBlock:^(ALAsset *asset)
{
ALAssetRepresentation *rep = [asset defaultRepresentation];
Byte *buffer = (Byte*)malloc(rep.size);
NSUInteger buffered = [rep getBytes:buffer fromOffset:0.0 length:rep.size error:nil];
NSData *data = [NSData dataWithBytesNoCopy:buffer length:buffered freeWhenDone:YES];//this is NSData may be what you want
[data writeToFile:photoFile atomically:YES];//you can save image later
}
failureBlock:^(NSError *err) {
NSLog(@"Error: %@",[err localizedDescription]);
}];