How to tell if blocks in loop all have completed executing?

Question

I have a loop set up that downloads a series a images which I will later use for to animate using the animationImages property of UIImageView. I wo

Answer 1

for (PFObject *pictureObject in objects){

    PFFile *imageFile = [pictureObject objectForKey:@"image"];
    NSURL *imageFileURL = [[NSURL alloc] initWithString:imageFile.url];
    NSURLRequest *imageRequest = [NSURLRequest requestWithURL:imageFileURL];

    [tokenImageView setImageWithURLRequest:imageRequest placeholderImage:nil success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {
       [self.downloadedUIImages addObject:image]; //This is a mutableArray that will later be set to an UIImageView's animnationImages
       if([[objects lastObject] isEqual:pictureObject]) {
           [self animateImages];
       }
    } failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error) {
        NSLog(@"Error %@", error);
        if([[objects lastObject] isEqual:pictureObject]) {
           [self animateImages];
       }
    }];

}

- (void)animateImages {
    //do animation here.
}