Question

I have a value that I’m retrieving from a block that I’d like to return in the below method. Being that it appears the block is asynchronous, how can I accomplish this?

-(UIImage*) imageAtIndex:(NSUInteger)index
{
    UIImage *image;
    [self.album enumerateAssetsAtIndexes:[NSIndexSet indexSetWithIndex:index] options:0 usingBlock: ^(ALAsset *result, NSUInteger index, BOOL *stop)
     {
            //set image in here
     }];

    return image;
}

Answer 1

I had done it like this in the past, check it.

-(void) imageAtIndex:(NSUInteger)index //since block is async you may not be able to return the image from this method
{

    UIImage *image;
    [self.album enumerateAssetsAtIndexes:[NSIndexSet indexSetWithIndex:index] options:0 usingBlock: ^(ALAsset *result, NSUInteger index, BOOL *stop)
     {
         //set image in here
          dispatch_async(dispatch_get_main_queue(), ^{ //if UI operations are done using this image, it is better to be in the main queue, or else you may not need the main queue.
             [self passImage:image]; //do the rest of the things in `passImage:` method
          });
     }];
}