1. Is your delegate sizeForItemAtIndexPath returning 0? - the delegate method cellForItemAtIndexPath will not be called if the item size is determined to be zero.
2. did you set a delegate and datasource for your uicollectionview? - The uicollectionview must get it's data from somewhere.
3. Is your cell size > your uicollectionview size? - if the set dimension (width or height) of your cell is too large, it will not be able to display the cell.