UICollectionView Disappear - ios

Question

I'm quite new to Swift. My problem is that my UICollectionView is disappearing.
In Xcode, it shows that everything is in place, but when I launch on a simulator or a device it disappears only left with the Navigation Bar and the Tab Bar.
Does anyone know what caused this or how to solve this?
Cheers!
Here is my code:
class User: UICollectionViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
override func numberOfSections(in collectionView: UICollectionView) -> Int {
// #warning Incomplete implementation, return the number of sections
return 0
}
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
// #warning Incomplete implementation, return the number of items
return 0
}
override func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
let header = collectionView.dequeueReusableSupplementaryView(ofKind: UICollectionElementKindSectionHeader, withReuseIdentifier: "Header", for: indexPath) as! UserHeaderView
header.userEmail.text = PFUser.current()!.email
header.userChosenName.text = PFUser.current()!.object(forKey: "nickname") as? String
header.profilePicture.layer.cornerRadius = header.profilePicture.frame.size.width/2
header.profilePicture.clipsToBounds = true
let query = PFUser.current()?.object(forKey: "profilePicture") as! PFFile
query.getDataInBackground { (image, error) in
if error == nil {
header.profilePicture.image = UIImage(data: image!)
}
else {
SVProgressHUD.showError(withStatus: "Something's Wrong...")
}
}
return header
}

Answer 1

You are using the generated class and you have the number of sections 0 and number of rows 0 you have to change those based the count you want them to show
override func viewDidLoad() {
super.viewDidLoad()
}
override func numberOfSections(in collectionView: UICollectionView) -> Int {
// The number of sections you have to provide
return 1
}
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
// Number of Items in this section at least it should be 1
return 1
}
override func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
let header = collectionView.dequeueReusableSupplementaryView(ofKind: UICollectionElementKindSectionHeader, withReuseIdentifier: "Header", for: indexPath) as! UserHeaderView
header.userEmail.text = PFUser.current()!.email
header.userChosenName.text = PFUser.current()!.object(forKey: "nickname") as? String
header.profilePicture.layer.cornerRadius = header.profilePicture.frame.size.width/2
header.profilePicture.clipsToBounds = true
let query = PFUser.current()?.object(forKey: "profilePicture") as! PFFile
query.getDataInBackground { (image, error) in
if error == nil {
header.profilePicture.image = UIImage(data: image!)
}
else {
SVProgressHUD.showError(withStatus: "Something's Wrong...")
}
}
return header
}
Edit:
You should have a cellForItemAt indexPath func else app will crash. here is an example of the function
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
// this will return an empty cell where you're app will not crash
// but you have to create a cell and populate some data to the cell
return UICollectionViewCell()
}