Whenever we use Collection View to get data, we must conform to a protocol. A protocol is a set of methods to which we have access, and can either be required or optional. For Collection Views, we are required to implement three methods to get data into a Collection View. So, let's add the following four functions (each beginning with func) after the closing curly bracket of viewDidLoad():

Let's break down the code to better understand what we are doing:

• Part A: This first method is what we need to add a header to our Collection View:

collectionView(_:viewForSupplementaryElementOfKind:at:)

• Part B: The identifier is what we added when we were designing in earlier chapters. This identifier helps Xcode know what view we are referring to:

let headerView = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "header", for: indexPath)
return headerView

• Part C: Our next method gets called for every item we need. Therefore, in our case, it gets called 20 times:

collectionView(_:cellForItemAt:)

• Part D: Here, we are creating a cell every time collectionView(_:numberOfItemsInSection:) is called. The identifier, exploreCell, is the name we gave it in the storyboard; so, this is the cell that is grabbed and used inside of our Collection View:

return collectionView.dequeueReusableCell(withReuseIdentifier: "exploreCell", for: indexPath)

• Part E: This method tells our Collection View how many different sections we want to display:

numberOfSections(in collectionView: UICollectionView)

• Part F: Here, we are telling our Collection View that we only want one section:

return 1

• Part G: Our next method tells our Collection View how many different items we are going to display inside of the section we set up:

collectionView(_:numberOfItemsInSection:)

• Part H: We are telling our Collection View that we want to display 20 items:

return 20

• Part I: Finally, we add this line back as it was removed. We use this function to dismiss our location modal when you hit the Cancel button:

@IBAction func unwindLocationCancel(segue:UIStoryboardSegue) {}

Let's build and run the project by hitting the Play button (or using command + R). We are now finished.