why is collection view header loading before viewdidload? - ios

Question

I am trying to add a activity indicator but I am not able to do so successfully because my collection view header is loading before viewdidload so therefore I have things showing before my activity indicator even starts. Can someone please help me or point me in the right direction. I have posted my code below
viewDidLoad
override func viewDidLoad() {
super.viewDidLoad()
fetchUser()
profileCollectionView?.register(guestHeaderCollectionViewCell.self, forSupplementaryViewOfKind: UICollectionElementKindSectionHeader, withReuseIdentifier: "headerId")
profileCollectionView?.register(photoViewCollectionViewCell.self, forCellWithReuseIdentifier: cellId)
}
func fetchUser() {
self.activityIndicator.startAnimating()
if let uid = selectedUser.uid{
Database.fetchUserWithUID(uid: uid) { (user) in
self.selectedUser = user
self.navigationItem.title = self.selectedUser?.fullName
self.profileCollectionView?.reloadData()
self.activityIndicator.stopAnimating()
self.activityIndicator.isHidden = true
self.fetchOrderedPosts()
}
}
}
Collection view header thats being called before viewDidLoad
func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
let header = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "headerId", for: indexPath) as! guestHeaderCollectionViewCell
header.user = self.selectedUser
header.delegate = self
return header
}
view controller
class newGuestPhotoViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout, UICollectionViewDataSource, guestProfileHeaderDelegate, HomePostCellDelegate {
let cellId = "cellId"
let homePostCellId = "homePostCellId"
#IBOutlet weak var profileCollectionView: UICollectionView!
#IBOutlet weak var activityIndicator: UIActivityIndicatorView!
var user: userAccount?
var selectedUser: userAccount!
var posts = [Post]()
let stringID = NSUUID().uuidString
var isGridView = true
func didChangeToGridView() {
isGridView = true
profileCollectionView?.reloadData()
}
func didChangeToListView() {
isGridView = false
profileCollectionView?.reloadData()
}
var showDataFlag : Bool = false!
override func viewDidLoad() {
super.viewDidLoad()
fetchUser()
profileCollectionView?.register(guestHeaderCollectionViewCell.self, forSupplementaryViewOfKind: UICollectionElementKindSectionHeader, withReuseIdentifier: "headerId")
profileCollectionView?.register(photoViewCollectionViewCell.self, forCellWithReuseIdentifier: cellId)
profileCollectionView?.register(newsfeedCollectionViewCell.self, forCellWithReuseIdentifier: homePostCellId)
}
func fetchUser() {
self.activityIndicator.startAnimating()
if let uid = selectedUser.uid{
Database.fetchUserWithUID(uid: uid) { (user) in
self.selectedUser = user
self.navigationItem.title = self.selectedUser?.fullName
self.showDataFlag = true;
self.profileCollectionView?.reloadData()
self.activityIndicator.stopAnimating()
self.activityIndicator.isHidden = true
self.fetchOrderedPosts()
}
}
}
fileprivate func fetchOrderedPosts() {
guard let uid = selectedUser?.uid else { return }
let ref = Database.database().reference().child("post").child(uid)
ref.queryOrdered(byChild: "dateOfPost").observe(.childAdded, with: { (snapshot) in
guard let dictionary = snapshot.value as? [String: Any] else { return }
let uid = dictionary["postUserUID"] as? String
Database.fetchUserWithUID(uid: uid!, completion: { (userSnap) in
let post = Post(user:userSnap, dictionary: dictionary)
self.posts.insert(post, at: 0)
guard let uid = Auth.auth().currentUser?.uid else {return}
Database.database().reference().child("likes").child(post.postID!).child(uid).observeSingleEvent(of: .value, with: { (snapshot) in
print(snapshot)
if let value = snapshot.value as? Int, value == 1 {
post.hasLiked = true
} else {
post.hasLiked = false
}
DispatchQueue.main.async(execute: {
self.profileCollectionView?.reloadData()
})
}, withCancel: { (err) in
print("Failed to fetch like info for post:", err)
})
})
}) { (err) in
print("Failed to fetch ordered posts:", err)
}
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
if(!showDataFlag){
return 0
}
return posts.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if isGridView {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath) as! photoViewCollectionViewCell
cell.post = posts[indexPath.item]
return cell
} else {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: homePostCellId, for: indexPath) as! newsfeedCollectionViewCell
cell.post = posts[indexPath.item]
cell.delegate = self
return cell
}
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
return 1
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
return 1
}
func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
let header = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "headerId", for: indexPath) as! guestHeaderCollectionViewCell
header.user = self.selectedUser
header.delegate = self
return header
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
return CGSize(width: view.frame.width, height: 250)
}

Answer 1

As I said in mi comment, you can add a flag and after your fetchUser() you can set this flag true and your collectionView will show your data
something like this
var showDataFlag : Bool = false
override func viewDidLoad() {
super.viewDidLoad()
fetchUser()
profileCollectionView?.register(guestHeaderCollectionViewCell.self, forSupplementaryViewOfKind: UICollectionElementKindSectionHeader, withReuseIdentifier: "headerId")
profileCollectionView?.register(photoViewCollectionViewCell.self, forCellWithReuseIdentifier: cellId)
}
func fetchUser() {
self.activityIndicator.startAnimating()
if let uid = selectedUser.uid{
Database.fetchUserWithUID(uid: uid) { (user) in
self.selectedUser = user
self.navigationItem.title = self.selectedUser?.fullName
self.showDataFlag = true;
self.profileCollectionView?.reloadData()
self.activityIndicator.stopAnimating()
self.activityIndicator.isHidden = true
self.fetchOrderedPosts()
}
}
}
//In your Collection View Data Source Implementation
func numberOfSections(in collectionView: UICollectionView) -> Int {
if(!showDataFlag){
return 0
}
return yourNeededNumberOfSections
}