I have a lite problem, I cannot recover the carte value in my database. when i get there for username. But the path is good.
My code :
override func viewDidLoad() {
super.viewDidLoad()
loadCarte()
}
func loadCarte(){
var ref: DatabaseReference!
ref = Database.database().reference()
let userID = Auth.auth().currentUser?.uid
ref.child("users").child(userID!).observeSingleEvent(of: .value, with: { (snapshot) in
// Get user value
let value = snapshot.value as? NSDictionary
let Carte = value?["carte"] as? String ?? ""
self.carteButton.setTitle(Carte + " cartes", for: .normal)
// ...
}) { (error) in
print(error.localizedDescription)
}
}
I manage to recover other values but not that one, can that come from the fact that its being an Integer?
Thank's in Advance
EDIT : my Json structure of a User Type under users > userID
{
"carte" : 10,
"email" : "apperce.v#gmail.com",
"username" : "vicro87000"
}
You're storing a numeric value in the carte property, so you're casting a numeric value to a string. In Swift you can't cast a number to a string like that.
I've been told by a Swift expert that this is the best way to accomplish the same:
let carte = value?["carte"].flatMap { $0 as? Int } .map { String($0) }
The flatMap operation here unwraps the int value from inside the optional that it's in. Then the map converts the int value to a string. Calling the String initializer in the map closure is required because Swift Ints are not castable to String types.
Assuming you're structure is:
uid_0
"carte" : 10,
"email" : "apperce.v#gmail.com",
"username" : "vicro87000"
And you want to read in the child values, here's some code to read that node
let thisUser = ref.child("users").child(uid)
thisUser.observeSingleEvent(of: .value, with: { snapshot in
let email = snapshot.childSnapshot(forPath: "email").value as? String ?? "No email"
let userName = snapshot.childSnapshot(forPath: "username").value as? String ?? "No username"
let carte = snapshot.childSnapshot(forPath: "carte").value as? Int ?? 0
print(email, username, carte)
})
So the carte var will be an Int and can be used in a label
myTextField.text = "\(carte)"
or cast to a String
let myIntAsString = String(carte)
this
as? Int ?? 0
is called a nil coalescing operator and protects your code in case the value is set to nil, it actually is set to 0 so you're code doesn't crash.
As a side note, this is dangerous
userID!
as force-unwrapping an optional can lead to a crash
Better to do
guard let user = Auth.auth().currentUser else {return}
let uid = user.uid
Related
I can fetch the user data from the firebase, but I cannot input the user data to a global variable.
Database.database().reference().child("users").child(userID!).observeSingleEvent(of: .value, with: { (snapshot) in
// Get user value
let value = snapshot.value as? NSDictionary
let username = value?["username"] as? String ?? ""
let userDigit = value?["lastDigit"] as? String ?? ""
let userDate = value?["babyDate"] as? String ?? ""
print(username)
print(userDigit)
print(userDate)
self.user.userName = username
self.user.userDigit = userDigit
self.user.userDate = userDate
}) { (error) in
print(error.localizedDescription)
}
print(self.user.userName)
print(self.user.userDigit)
print(self.user.userDate)
From the above code, I can see the username, userDigit, userDate, however, after i input the data into user class that contains 3 string variables, i cannot print the user class value.
To be specific,
print(self.user.userName)
this code returns nil.
How can I input the data?
The value of self.user.userName is nil because you're calling it outside the observer closure.
Printing a value after assigning in a closure doesn't guarantee that it will be available immediately afterwards.
Because the closure of observeSingleEvent gets called after the data is fetched from firebase.
You should modify your logic and try to access the value of user after the data has successfully been fetched from firebase.
below is a sample code that might help you understand the concept:
func getUser(with userID: String, completion: #escaping ((_ user: User) -> Void)) {
Database.database().reference().child("users").child(userID).observeSingleEvent(of: .value) { (snapshot) in
// Get user value
let value = snapshot.value as? [String: Any]
let username = value?["username"] as? String ?? ""
let userDigit = value?["lastDigit"] as? String ?? ""
let userDate = value?["babyDate"] as? String ?? ""
var user = User()
user.userName = username
user.userDigit = userDigit
user.userDate = userDate
DispatchQueue.main.async {
completion(user)
}
}
}
In the above method, we fetch data from firebase and return it inside a closure of our own once the data is available.
and then you call the above function like this:
self.getUser(with: userID!) { (user) in
// the user object inside the closure will be available after fetching data from firebase
// the user object can even be assigned to a global property
self.globalUser = user
print(self.globalUser.userName)
print(self.globalUser.userDigit)
print(self.globalUser.userDate)
}
Hope this helps
I've got a code which normally should return to me a value from Firebase.
My Firebase struct is :
Experience{
UserId{
LDG_DAY: "4"
LDG_NIGHT: "0"
APCH_IFR: "0"
}
}
My code is :
func getUserExp(){
let ref = Database.database().reference()
let userID = Auth.auth().currentUser?.uid
let Date = self.flightDate.text
ref.child("Experience")/*.child(userID!)*/.observeSingleEvent(of: .value) {(snapshot) in
if snapshot.hasChild(userID!){
let value = snapshot.value as? NSDictionary
let ldg_day = value?["LDG_DAY"] as? String ?? "123"
let ldg_night = value?["LDG_NIGHT"] as? String ?? "0"
let apch_ifr = value?["APCH_IFR"] as? String ?? "0"
self.intLdgDay = Int(ldg_day)!
self.intLdgNight = Int(ldg_night)!
self.intApchIfr = Int(apch_ifr)!
print("string = \(ldg_day) int = \(self.intLdgDay)")
}
}
}
Now the code didn't work as I would like... In fact my code return the basic as? String ?? "123" value but the snapshot.value get the good value from firebase ...
What's wrong ? I use this code for many other part of my app and no problems about it ?
Thanks for your help
I believe you want to ensure the node exists before trying to read the child data.
NOTE:
I see the path to read has the uid commented out so it's unclear if you intended to read a single user (leaving in the uid) or if you actually wanted to load every user at one time (thousands). This answer assumes you are intending to read that specific user node only. See #Callam answer if you intended to read ALL of the users nodes at one time.
The code you have now is using snapshot.hasChild which looks within the node to see if the child, the users uid exists, and it doesn't so the code will always fail.
if snapshot.hasChild(userID!)
I think what you want to do is use snapshot.exists to ensure it's a valid node before reading. Here's the code:
let experienceRef = self.ref.child("Experience")
let usersExpRef = experienceRef.child(uid)
usersExpRef.observeSingleEvent(of: .value) { snapshot in
if snapshot.exists() {
let value = snapshot.value as! [String: Any]
let ldg_day = value["LDG_DAY"] as? String ?? "123"
print("string = \(ldg_day)")
} else {
print("the \(uid) node does not exist")
}
}
I would also suggest safely unwrapping options before attempting to work with them as they could be nil, and that would crash your code.
guard let thisUser = Auth.auth().currentUser else { return }
let uid = thisUser.uid
Note I also replaced the old objc NSDictionary with it's Swifty counterpart [String: Any]
Assuming your struct is from the root, and Experience contains more than one user ID, your code is currently observing the value for all user IDs since the /*.child(userID!)*/ is commented out.
Therefore you are requesting every user's experience and checking on the client if the current user exists as a child – this will succeed if the current user's ID is present at Experience/$uid.
ref.child("Experience")/*.child(userID!)*/.observeSingleEvent(of: .value) { (snapshot) in
if snapshot.hasChild(userID!) {
let value = snapshot.value as? NSDictionary
Now we have a snapshot with all Experiences and we've confirmed that it has a child for the current user's ID – we would need to get that child and cast the value of that to a dictionary.
let value = snapshot.childSnapshot(forPath: userID).value as? NSDictionary
This fixes the issue but obviously, we don't want to download every experience on a single user's device, and they maybe shouldn't even have the permission to request that reference location either.
So if you uncomment .child(userID!), the snapshot will be of just one Experience, so snapshot.hasChild(userID!) will fail. Instead, you can use snapshot.exists() and/or a conditional cast to determine if the snapshot for the userID is existent and/or thereby castable.
func getUserExp() {
let ref = Database.database().reference()
let userID = Auth.auth().currentUser?.uid
let Date = self.flightDate.text
ref.child("Experience").child(userID!).observeSingleEvent(of: .value) { snapshot in
if snapshot.exists() {
let value = snapshot.value as? [String:String]
let ldg_day = value?["LDG_DAY"] ?? "123"
let ldg_night = value?["LDG_NIGHT"] ?? "0"
let apch_ifr = value?["APCH_IFR"] ?? "0"
self?.intLdgDay = Int(ldg_day)!
self?.intLdgNight = Int(ldg_night)!
self?.intApchIfr = Int(apch_ifr)!
print("string = \(ldg_day) int = \(self.intLdgDay)")
} else {
print("experience for \(snapshot.key) doesn't exist")
}
}
}
You can clean this up a bit with a struct and extension.
// Experience.swift
struct Experience {
var ldg_day: String
var ldg_night: String
var apch_ifr: String
}
extension Experience {
static var currentUserRef: DatabaseReference? {
return Auth.auth().currentUser.flatMap {
return Database.database().reference(withPath: "Experience/\($0.uid)")
}
}
init?(snapshot: DataSnapshot) {
guard snapshot.exists() else { return nil }
let value = snapshot.value as? [String:String]
self.ldg_day = value?["LDG_DAY"] ?? "123"
self.ldg_night = value?["LDG_NIGHT"] ?? "0"
self.apch_ifr = value?["APCH_IFR"] ?? "0"
}
}
Et voilà,
func getUserExp() {
Experience.currentUserRef?.observeSingleEvent(of: .value, with: { [weak self] in
if let experience = Experience(snapshot: $0) {
self?.intLdgDay = Int(experience.ldg_day)!
self?.intLdgNight = Int(experience.ldg_night)!
self?.intApchIfr = Int(experience.apch_ifr)!
print("string = \(experience.ldg_day) int = \(self.intLdgDay)")
} else {
print("experience for \($0.key) doesn't exist")
}
})
}
Here is the output of "print(dict)"...
["2018-10-17 11:19:51": {
firstname = Brooke;
id = 40vI7hApqkfX75SWsqIR6cdt7xV2;
lastname = Alvarez;
message = hshahyzhshbsbvash;
username = poiii;
}]
["2018-10-17 11:20:31": {
firstname = Trevor;
id = 40vI7hApqkfX75SWsqIR6cdt7xV2;
lastname = Bellai;
message = hey;
username = br9n;
}]
["2018-10-17 11:20:44": {
firstname = Amy;
id = 40vI7hApqkfX75SWsqIR6cdt7xV2;
lastname = Ikk;
message = hey;
username = nine9;
}]
My code...
Database.database().reference().child("recent-msgs").child(uid!).observe(.childAdded) { (snapshot: DataSnapshot) in
if let dict = snapshot.value as? [String: Any] {
print(dict)
// Store data in user.swift model
let firstnameData = dict[0]["firstname"] as! String
let idData = dict["id"] as! String
let lastnameData = dict["lastname"] as! String
let messageData = dict["message"] as! String
let usernameData = dict["username"] as! String
let rankData = dict["rank"] as! String
let propicrefData = dict["propicref"] as! String
let convoinfo = RecentConvo(firstnameString: firstnameData, idString: idData, lastnameString: lastnameData, messageString: messageData, usernameString: usernameData, rankString: rankData, propicrefString: propicrefData)
self.recentconvos.append(convoinfo)
print(self.recentconvos)
self.tableView.reloadData()
}
}
I'm trying to retrieve the dictionary within the first dictionary which is the value to the key which is the date associate with it. For example: 2018-10-17 11:19:51. However I cannot use this exact string to call it because I must do this without the knowledge of that string.
I tried this:
let firstnameData = dict[0]["firstname"] as! String
But it returns an error:
Cannot subscript a value of type '[String : Any]' with an index of type 'Int'
The error noted above is showing up because you were trying to access the element at a certain position (0) from the dictionary. Dictionaries are not ordered lists, and hence won't have a fixed order of elements to be accessed.
The logged dictionary doesn't really look like a dictionary. Assuming that it is a dictionary, and its keys are the date strings, you can use the following code snippet to parse the dictionary.
class RecentConversation {
var id: String?
var firstName: String?
var lastName: String?
var message: String?
var username: String?
var rank: String?
var propicref: String?
init?(dictionary: [String: Any]?) {
guard let dict = dictionary else {
// Return nil in case the dictionary passed on is nil
return nil
}
id = dict["id"] as? String
firstName = dict["firstname"] as? String
lastName = dict["lastname"] as? String
message = dict["message"] as? String
username = dict["username"] as? String
rank = dict["rank"] as? String
propicref = dict["propicref"] as? String
}
}
Usage:
let dateStrings = dict.keys.sorted {
// Sort in chronological order (based on the date string; if you need to sort based on the proper date,
// convert the date string to Date object and compare the same).
//
// Swap the line to $0 > $1 to sort the items reverse chronologically.
return $0 < $1
}
var conversations: [RecentConversation] = []
for date in dateStrings {
if let conversation = RecentConversation(dictionary: (dict[date] as? [String: Any])) {
conversations.append(conversation)
}
}
You were all very helpful, so I would like to start off by saying thank you. I went ahead and applied the method that lionserdar explained. (.allKeys)
// Fetch Recent Messages
func fetchRecentMsgs() {
// Direct to database child
Database.database().reference().child("recent-msgs").child(uid!).observe(.childAdded) { (snapshot: DataSnapshot) in
if let dict = snapshot.value as? NSDictionary {
print(dict)
print(dict.allKeys)
let keys = dict.allKeys
for key in keys {
print(key)
if let nestedDict = dict[key] as? [String: Any] {
print(nestedDict)
let firstnameData = nestedDict["firstname"] as! String
let idData = nestedDict["id"] as! String
let lastnameData = nestedDict["lastname"] as! String
let messageData = nestedDict["message"] as! String
let usernameData = nestedDict["username"] as! String
Worked for me so I hope this will help others too!
I am fairly new to the Swift syntax and am receiving this error with my code "Cannot assign through subscript: subscript is get only"
This is from the line: friendDictionary[(friendUID as? String)!] = ["name": friendsData!["name"]]
Any advice on the correct way of doing it would be very helpful.
func getFriendsUIDs() {
if FBSDKAccessToken.currentAccessToken() == nil {
print("failed to start graph request")
return
}else{
}
if FBSDKAccessToken.currentAccessToken() != nil {
}
let parameters = ["fields": "name, id, picture"]
FBSDKGraphRequest(graphPath: "/me/friends", parameters: parameters).startWithCompletionHandler {
(NSURLConnection, result, requestError) in
let friendIds = result["id"] as? NSDictionary
let friendsData = friendIds!["data"] as? [NSDictionary]
var ref: FIRDatabaseReference!
ref = FIRDatabase.database().reference()
ref.child("users").child((FIRAuth.auth()?.currentUser?.uid)!).child("friendUIDs").observeEventType(.Value, withBlock: { (snapshot) in
self.FriendUIDs = NSArray()
self.FriendUIDs = (snapshot.value as? NSArray)!
print(self.FriendUIDs)
var friendDictionary = NSDictionary()
for friendUID in self.FriendUIDs {
friendDictionary[(friendUID as? String)!] = ["name": friendsData!["name"]]
}
self.fetchFriendFeed(friendDictionary)
}) { (error) in
print(error.localizedDescription)
}
}
}
func fetchFriendFeed(friendDictionary: NSDictionary) {
var ref: FIRDatabaseReference!
ref = FIRDatabase.database().reference()
for friendUID in FriendUIDs {
ref.child("users").child(friendUID as! String).child("Agenda").observeEventType(.ChildAdded, withBlock: { (snapshot) in
print(snapshot)
if let dictionary = snapshot.value as? [String: AnyObject] {
let friendPost = FriendPost()
friendPost.picture = friendDictionary[friendUID as! String]? ["picture"] as? String
friendPost.activity = dictionary["activity"] as? String
friendPost.date = dictionary["date"] as? String
friendPost.time = dictionary["time"] as? String
friendPost.friendname = friendDictionary[friendUID as! String]? ["name"] as? String
self.friendPosts.append(friendPost)
dispatch_async(dispatch_get_main_queue(), {
self.collectionView?.reloadData()
Nothing to do with Swift. You've elected to use Objective-C, in effect, by making friendDictionary an NSDictionary. NSDictionary is immutable; you can't assign into it or alter it in any way. That is simply a fact about Objective-C. The Swift var declaration makes no difference to this fact.
A better choice, since you are writing in Swift, would be to use a Swift dictionary, which is [AnyHashable:Any]() (in Swift 3). This will interchange with NSDictionary when you are talking to Objective-C, but it will give you a mutable dictionary because you (rightly) declared it with var.
Have you tried using NSMutableDictionary? That solved the issue for me.
For those who get stuck here, another reason for this happens when you try to assign something that does not conform the actual dictionary, in my example i was doing something like this:
var dict = [Date : UUID]()
let randomUUID = UUID()
dict[randomUUID] = Date.now
whereas I meant to write UUID : Date but I was sleepy so i made a mistake, and Swift gave me a misleading error saying subscript is get-only. So this error also appears with type mismatch for Swift 5.7.
I am on point where I gotta compare non optional value with nil. But I can't do it because Xcode says:
Comparing non-optional value of type 'Int' to nil always returns false
So I created Struct and then made variable: var products: [Product] = []
How I am able to compare it with nil?:
if products[indexPath.row].snusPortions == nil
{
cell.snusPortionsAmountLabel.text = "N/A"
}else
{
cell.snusPortionsAmountLabel.text = String(products[indexPath.row].snusPortions)
}
I've assigned values to them like this:
let ref = FIRDatabase.database().reference().child("Snuses").queryOrdered(byChild: "Brand").queryEqual(toValue: brandName)
ref.observeSingleEvent(of: .value, with: { (snapshot) in
if snapshot.exists(){
let enumerator = snapshot.children
while let thisProduct = enumerator.nextObject() as? FIRDataSnapshot
{
print(thisProduct.value) // So I may see what the data is like and know how to extract it
// Chances are you'd have to create a dictionary
let thisProductDict = thisProduct.value as! [String:AnyObject]
let productName = thisProductDict["Products"] as! String
let snusPortions = thisProductDict["PortionsCan"] as? Int
let productObject = Product(snusProductTitle: productName, snusNicotine: snusNicotine, snusPortions: snusPortions!, snusFlavor: snusFlavor, snusWeight: snusWeight!, snusShippingWeight: snusShippingWeight, snusProductImageURL: productURL)
self.products.append(productObject)
print(self.products)
}
self.tableView.reloadData()
}
})
This is Product struct:
struct Product {
var snusProductTitle: String
init()
{
snusProductTitle = ""
}
init(snusProductTitle: String){
self.snusProductTitle = snusProductTitle
}
}
While testing it says snusPortions is nil but I said to make it "N/A" if it is nil, why?
It sounds like you are confusing yourself between the local variable snusPortions and the Product property snusPortions.
In your Product definition, the property snusPortions is an Int. It can never be nil. Hence, in this code:
if products[indexPath.row].snusPortions == nil
... this Product's snusPortions will never be nil, and we will never set the text to "N/A".
Now let's look at your other code:
let snusPortions = thisProductDict["PortionsCan"] as? Int
This is a completely different snusPortions. It can be nil, namely, if thisProductDict lacks a "PortionsCan" key or if its value is not castable to Int.