UICollectionViewCell Border / Shadow

Just for a bit more implementation:

#import <QuartzCore/QuartzCore.h>

in your.m

Make sure your class implements

- (UICollectionViewCell *)collectionView:(UICollectionView *)cv cellForItemAtIndexPath:(NSIndexPath *)indexPath; 

as this is where the cell is setup.

You can then change cell.layer.background (only available once quartz is imported)

See below

- (UICollectionViewCell *)collectionView:(UICollectionView *)cv cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    MyCollectionViewCell *cell = [cv dequeueReusableCellWithReuseIdentifier:@"pressieCell" forIndexPath:indexPath];
    //other cell setup here

    cell.layer.borderWidth=1.0f;
    cell.layer.borderColor=[UIColor blueColor].CGColor;

    return cell;
}