MVVMExample.m

//
// View Controller
//

- (void) viewDidLoad {
    [super viewDidLoad];

    RAC(self.viewModel, username) = [myTextfield rac_textSignal];

    RACSignal *usernameIsValidSignal = RACObserve(self.viewModel, usernameValid);

    RAC(self.goButton, alpha) = [usernameIsValidSignal
        map: ^(NSNumber *valid) {
            return valid.boolValue ? @1 : @0.5;
        }];

    RAC(self.goButton, enabled) = usernameIsValidSignal;

    RAC(self.avatarImageView, image) = RACObserve(self.viewModel, userAvatarImage);
    
    RAC(self.userNameLabel, text) = RACObserve(self.viewModel, userFullName);

    @weakify(self);
    [[[RACSignal merge:@[RACObserve(self.viewModel, tweets),
                        RACObserve(self.viewModel, allTweetsLoaded)]]
        bufferWithTime:0 onScheduler:[RACScheduler mainThreadScheduler]]
        subscribeNext:^(id value) {
            @strongify(self);
            [self.tableView reloadData];
        }];
    
    [[self.goButton rac_signalForControlEvents:UIControlEventTouchUpInside]
        subscribeNext: ^(id value) {
            @strongify(self);
            [self.viewModel getTweetsForCurrentUsername];
        }];
}

-(UITableViewCell*)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    // if table section is the tweets section
    if (indexPath.section == 0) {
        MYTwitterUserCell *cell =
        [self.tableView dequeueReusableCellWithIdentifier:@"MYTwitterUserCell" forIndexPath:indexPath];
        
        // grab the cell view model from the vc view model and assign it
        cell.viewModel = self.viewModel.tweets[indexPath.row];
        return cell;
    } else {
        // else if the section is our loading cell
        MYLoadingCell *cell =
        [self.tableView dequeueReusableCellWithIdentifier:@"MYLoadingCell" forIndexPath:indexPath];
        [self.viewModel loadMoreTweets];
        return cell;
    }
}


//
// MYTwitterUserCell
//

// this could also be in cell init
- (void) awakeFromNib {
    [super awakeFromNib];
    
    RAC(self.avatarImageView, image) = RACObserve(self, viewModel.tweetAuthorAvatarImage);
    RAC(self.userNameLabel, text) = RACObserve(self, viewModel.tweetAuthorFullName);
    RAC(self.tweetTextLabel, text) = RACObserve(self, viewModel.tweetContent);
}

[self.tableView loadMoreTweets]; should be [self.viewModel loadMoreTweets];