Setting delegate to self for the collection view after present action - ios

Question

There are 2 pages in Main.storyboard: FirstViewController and SecondViewController
There is a button in FirstViewController. Here is the button click scope:
let controller = SecondViewController()
present(controller, animated: true, completion: nil)
And there is a collection view component in SecondViewController.
import UIKit
class SecondViewController: UIViewController {
#IBOutlet weak var collectionViewOutlet: UICollectionView!
override func viewDidLoad() {
super.viewDidLoad()
collectionViewOutlet.delegate = self
collectionViewOutlet.dataSource = self
let xib = UINib(nibName: "ViewCell", bundle: nil)
self.collectionViewOutlet.register(xib, forCellWithReuseIdentifier: "ViewCellID")
let v0 = self.storyboard?.instantiateViewController(withIdentifier: "subView") as! SubViewController
temp_containerViewController = v0
}
}
extension MainPageViewController: UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout
{
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return self.myPageList.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionViewOutlet.dequeueReusableCell(withReuseIdentifier: "ViewCellID", for: indexPath) as! ViewCell
let viewController = self.temp_containerViewController
cell.contentViewOutlet = viewController?.view
cell.contentViewOutlet.backgroundColor = .brown
cell.lblOutlet.text = self.myPageList[indexPath.row]
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return collectionViewOutlet.frame.size
}
func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
let index = self.collectionViewOutlet.contentOffset.x / self.collectionViewOutlet.frame.size.width
self.pageControlOutlet.currentPage = Int(index)
self.pageControlOutlet.numberOfPages = myPageList.count
}
}
but below code gives an error:
collectionViewOutlet.delegate = self
How can I fix this problem? I have created an outlet for the collection view component as you see above.
Here is the error sentence:
Thread 1: Fatal error: Unexpectedly found nil while implicitly unwrapping an Optional value

Answer 1

You need to load this line
let controller = SecondViewController()
From storyboard ( Give it identifier Second )
let controller = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "Second") as! SecondViewController
As you have outlets without XIB

Answer 2

Add a condition in numberOfItemsInSection func
Step 1.
if self.myPageList.count > 0 {
return self.myPageList.count
}else {
return 0
}
Step2. Set identifier
let controller = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "Second") as! SecondViewController
Hope Its Help