Updating array swift 4

Question

I am trying to update an image array by downloading image from firebase database. But for some reason, after the array is updated inside the function, it is not updated in the viewdidload function. I am new to xcode. Any ideas?

var images:[UIImage] = [] override func viewDidLoad() { super.viewDidLoad() ref = Database.database().reference() retrieveImage() print(self.images) } func retrieveImage(){ let userID = Auth.auth().currentUser?.uid ref.child("Images").observeSingleEvent(of: .value, with: { (snapshot) in let userImage = snapshot.value as? NSDictionary let imageURLArray = userImage?.allKeys if userImage != nil{ for index in 0...userImage!.count-1{ let imageProfile = userImage![imageURLArray?[index]] as? NSDictionary let imageURL = imageProfile!["url"] let storageRef = Storage.storage().reference(forURL: imageURL as! String) storageRef.getData(maxSize: 1 * 1024 * 1024) { data, error in if let error = error { print(error.localizedDescription) } else { let image = UIImage(data: data!) self.images.append(image!) } } } } }) { (error) in print(error.localizedDescription) } }

Since its an asynchronous call you need to wait until your images downloaded. — Dharmesh Kheni
– Dharmesh Kheni, Commented Dec 7, 2018 at 8:44

Mai Tuan · Accepted Answer · 2018-12-07 08:55:07Z

because observeSingleEvent runs asynchronously, the print function is called before observeSingleEvent finish. You can fix it like this, use closure

var images:[UIImage] = [] override func viewDidLoad() { super.viewDidLoad() ref = Database.database().reference() retrieveImage { print(self.images) } } func retrieveImage(_ completion: () -> Void){ let userID = Auth.auth().currentUser?.uid ref.child("Images").observeSingleEvent(of: .value, with: { (snapshot) in let userImage = snapshot.value as? NSDictionary let imageURLArray = userImage?.allKeys if userImage != nil{ for index in 0...userImage!.count-1{ let imageProfile = userImage![imageURLArray?[index]] as? NSDictionary let imageURL = imageProfile!["url"] let storageRef = Storage.storage().reference(forURL: imageURL as! String) storageRef.getData(maxSize: 1 * 1024 * 1024) { data, error in if let error = error { print(error.localizedDescription) } else { let image = UIImage(data: data!) self.images.append(image!) } } } } completion() }) { (error) in print(error.localizedDescription) completion() } }

becouse function storageRef.getData(maxSize: 1 * 1024 * 1024) { data, error in... is asynchronously. you can use dispath after some time to get images

Mai Tuan · Accepted Answer · 2018-12-07 10:43:02Z

you can use like this

var images:[UIImage] = [] override func viewDidLoad() { super.viewDidLoad() ref = Database.database().reference() retrieveImage { print(self.images) } } func retrieveImage(_ completion: () -> Void){ let userID = Auth.auth().currentUser?.uid ref.child("Images").observeSingleEvent(of: .value, with: { (snapshot) in let userImage = snapshot.value as? NSDictionary let imageURLArray = userImage?.allKeys if userImage != nil { for index in 0...userImage!.count-1 { let imageProfile = userImage![imageURLArray?[index]] as? NSDictionary let imageURL = imageProfile!["url"] let storageRef = Storage.storage().reference(forURL: imageURL as! String) storageRef.getData(maxSize: 1 * 1024 * 1024) { data, error in if let error = error { completion() print(error.localizedDescription) } else { let image = UIImage(data: data!) self.images.append(image!) if index == userImage!.count-1 { completion() } } } } } else { completion() } }) { (error) in print(error.localizedDescription) completion() } }

Collectives™ on Stack Overflow

Updating array swift 4

2 Answers 2

1 Comment

Comments

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Related