ios6 - UICollectionView from storyboard: is scrolling implemented by default?

Question

With XCode 4.6 building for iOS 6.1, I'm using a UICollectionView from a storyboard, and I thought that the class implemented scrolling by default. I have made a simple test app with a storyboard that has just a Collection View and one Collection View Cell, and code that implements just collectionView:cellForItemAtIndexPath: and collectionView:numberOfItemsInSection:, calling for enough cells so that scrolling is required to see all the cells.

I thought that with nothing else, I would be able to scroll vertically within the UICollectionView. It shows the visible cells but doesn't scroll. What am I missing here?

Why wouldn't this component allow me to scroll vertically, what am I unable to see?

The implementation code is about as simple as possible:

//
//  TestpViewController.h
//

#import <UIKit/UIKit.h>

@interface TestpViewController : UIViewController <UICollectionViewDataSource, UICollectionViewDelegate>

@end

//
//  TestpViewController.m
//

#import "TestpViewController.h"

@interface TestpViewController ()
@property (weak, nonatomic) IBOutlet UICollectionView *collectionView;

@end

@implementation TestpViewController

- (void)viewDidLoad
{   
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (NSInteger)collectionView:(UICollectionView *)collectionView
     numberOfItemsInSection:(NSInteger)section
{
    return 30;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView
                  cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"testCell" forIndexPath:indexPath];
    return cell;
}

@end