Inserting different sizes Images in UICollectionView In iOS

I am currently working in an iOS application in which i have to show images in collection view. I am working with following procedure :

1. 
   

   I am using below code for saving the image in collectionviewcontroller from my current controller.

   
   

   UICollectionViewFlowLayout *layout=[[UICollectionViewFlowLayout alloc]init]; layout.itemSize=CGSizeMake(320, 420); layout.minimumLineSpacing = -8.0; [layout setSectionInset:UIEdgeInsetsMake(0, 30, 0, 0)]; CollectionViewController *coll=[[CollectionViewController alloc]initWithCollectionViewLayout:layout ]; [self.navigationController pushViewController:coll animated:YES];

   
   

2: In collectionviewcontroller, i am inserting images with following method.

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
    int i;
    Cell *cell=[collectionView dequeueReusableCellWithReuseIdentifier:REUSEABLE_CELL_IDENTITY forIndexPath:indexPath];

    cell.layer.borderWidth=8.0f;

    @try
    {
    NSLog(@"index path is %ld",(long)indexPath.row);
        items =[ChildDetails getAllData];
        cdata =[AlbumDetails getAllData];
        revArray = [ChildDetails getAllDataDesc];

    cell.bounds=CGRectMake(0,0, 320, 420);

    if(rearr.count == 0)
    {
        NSLog(@"Do nothing");
        cell.imageviews.image=NULL;
    }
    else
    {

     NSLog(@"count %lu",(unsigned long)rearr.count);
    for (i=0;i<rearr.count; i++)
    {
        NSLog(@"count %lu",(unsigned long)rearr.count);
        image = [UIImage imageWithContentsOfFile:rearr[i]];
        if(image != nil)
        {
       [itms addObject:image];
        }
        else
        {
            NSData  *data = [[NSData alloc]initWithContentsOfFile:rearr[i]];
            image=[UIImage imageWithData:data];
            [itms addObject:image];
        }
    }

        cell.imageviews.contentMode = UIViewContentModeScaleAspectFit ;
        cell.imageviews.clipsToBounds=YES;

       cell.imageviews.image=[itms objectAtIndex:indexPath.row];
    }


    return cell;
    }
    @catch (NSException *exception)
    {
     return cell;
     }
}

Everything works fine , but the problem is when i insert the images whose width is greater than the height, in that scenario i get the white spaces in the cell. I have attach the image of my collection viewcontroller, so you can easily understand my problem. I had tried with the below code also :

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{
    UIImage *image = [imageArray objectAtIndex:indexPath.row];

    return CGSizeMake(image.size.width, image.size.height); 
}

I Know this is the only way by which i can get out from the issue but i am not getting the proper way how to use it for every image.

My requirement is when i select and insert different sizes images it will fit there properly.There will not be any white space between two images ,![I want to make the gallery like this in collection view so when i save any image of any size it will fit properly in the gallery.][1]

Please guide me the way.I am highly grateful to you.