I am designing a litte quiz app but I'm having trouble while retrieving the game data.
As you can see in the picture I have an JSON object that contains many single games. Each single game has a unique id. My first problem is that each of the games can be available in multiple languages. I know that I could download the hole snap and then looping throw each game but that would mean really long loading times while the app is growing.
In short form:
I need to retrieve the following data from the JSON above:
A random game wich is available in a specific language (need to have the key en for example)
All games that are available in "en" but not yet in "de"
If it is easier to restructure the data in the JSON, please tell me.
Thanks for helping me.
Answer to your first part :-
let enRef = FIRDatabase.database().reference().child("singleGames").child(singleGamesUID).child("en")
enRef.observeEventType(.Value, withBlock: {(snap) in
if let enQuizQuestion = snap.value as? [String:AnyObject]{
//Question exists : Retrieve Data
}else{
//Question in english doesn't exist
}
})
For your second part
Since you are trying to save iteration time might i suggest you also save your singleGames id in a separate languagesBased nodes, there is a command in firebase that allows you to search for some keyValues in your child node's , but even that i think would be executing a search algorithm which might be a little more time consuming :--
appServerName:{
singleGames :{
uid1:{......
......
...},
uid2:{......
......
...},
uid3:{......
......
...}
},
enQuestions:{
uid3 : true
}
deQuestions:{
uid1 : true,
uid2 : true
}
}
Now all you gotta do :-
let rootRef = FIRDatabase.database().reference().child("deQuestions").observeEventType(.Value, withBlock: {(qSnap) in
if let qDict = qSnap.value as? [String:AnyObject]{
for each in qDict as [String:AnyObject]{
let deUID = each.0
}
}else{
//No question in dutch language
}
})
Related
I know this question is asked a lot, but none of the solutions seem to be working for me(I have been trying multiple solutions from threads like Read data from firebase swift but it doesnt print anything to my console).
I am trying to retrieve the type of user from my database, but I dont know how to.
func pushUserInfo(){
let ref = Database.database().reference()
let infoDict = ["First name": firstName.text!, "Last name": lastName.text!, "hours": 0, "isUser" : "user"] as [String : Any]
let users = ref.child("users").child(username)
users.setValue(infoDict)
}
The part that says ["type": "user"] has two options, either "user" or admin
The screenshot above is of the Firebase realtime database.
I am trying to retrieve the type of the user, but I have no idea how. Please help me figure this out, and if possible, explain the code, because I dont really understand too much about Firebase in general. I tried reading their firebase docs, but I still dont really get it.
It looks like you're setting the data fine except that your username property appears to be a concatenated string of two optionals (maybe firstName.text and lastName.text. So this will make it impossible to query. The first step is to unwrap these into a string:
let username = "\(firstName.text!) \(lastName.text!)"
Once you've done that, you can query for that data like this:
let username = "\(firstName.text!) \(lastName.text!)"
let ref = Database.database().reference().child("users/\(username)")
ref.observeSingleEvent(of: .value, with: { (snapshot) in
// Now you can access the type value
let value = snapshot.value as? NSDictionary
let type = value?["type"] as? String ?? ""
}) { (error) in
print(error.localizedDescription)
}
You may also want to reconsider having spaces in your property names (maybe use lastName instead of last name). It will be easier for your code later on.
I am working on an app displaying places (downloaded from firebase) based on user location.
I have currently 5k entries and they are displayed in about 10seconds.
I plan to have 80k entries and I don't want users to wait that long.
What I did :
I created a Place class, I do 'observe'(.value) on my firebase ref and on each child I put each element in an attribute of the Place class.
Then the place:Place = Place(attributes) id added to an array:Place until all places have been downloaded.
self.ref.queryOrderedByKey().observe(.value, with: {(snapshot) in
if snapshot.childrenCount > 0 {
for place in snapshot.children.allObjects as! [DataSnapshot] {
When all places are in the array I compare places locations with the user location and sort the array to display them by distance in a tableview.
What I tried:
I also tried to use GeoFire but it is slower.
How the db looks like (80k elements) :
{
"users": {
"DFkjdhfgYG": {
"id":"DFkjdhfgYG"
,"key2":"value"
,"key3":"value"
,"key4":"value"
,"key5":"value"
,"key6":"value"
,"key7":"value"
,"key8":"value"
,"key9":"value"
,"key10":"value"
,"key11":"value"
,"key12":value
,"key13":value
,"key14":"value"
,"key15":"value"
,"key16":"value"
,"key17":"value"
,"key18":"value"
,"key19":"value"
,"key20":"value"
,"key21":value
,"key22":value
,"key23":value
,"key24":value
,"key25":value
,"key26":"value"
,"key27":value
,"key28":value
,"key29":"value"
},
"BVvfdTRZ": {
"id":"BVvfdTRZ"
,"key2":"value"
,"key3":"value"
,"key4":"value"
,"key5":"value"
,"key6":"value"
,"key7":"value"
,"key8":"value"
,"key9":"value"
,"key10":"value"
,"key11":"value"
,"key12":value
,"key13":value
,"key14":"value"
,"key15":"value"
,"key16":"value"
,"key17":"value"
,"key18":"value"
,"key19":"value"
,"key20":"value"
,"key21":value
,"key22":value
,"key23":value
,"key24":value
,"key25":value
,"key26":"value"
,"key27":value
,"key28":value
,"key29":"value"
}
}
}
Now I don't know what to do and I absolutely need to user Firebase.
Can you help me to improve the way I download firebase db elements, or to show me another way to do it, to make the whole process faster ?
Thanks !
You're using a for loop in a function that is being called the same number of times as there are children in your database path, making the for loop completely useless and overkill, which can add extra time to the whole process.
Another thing that you can do is have this be called on a different thread and making it the highest priority over the rest of your code. Here's how to do both of those:
func handleFirebase() {
DispatchQueue.global(qos: .userInteractive).async {
self.ref.queryOrderedByKey().observe(.value, with: { (snapshot) in
guard let value = snapshot.value as? String else { return }
let key = snapshot.key
print("KEY: \(key), VALUE: \(value)")
}, withCancel: nil)
}
}
override func viewDidLoad() {
super.viewDidLoad()
getImageUrl()
}
func getImageUrl(){
ref.child("posts").queryOrderedByKey().observeSingleEvent(of: .value) { (snapchot) in
let postsss = snapchot.value as! [String : AnyObject]
for (_,posst) in postsss {
if let uid = posst["userID"] as? String{
if uid == Auth.auth().currentUser?.uid{
if let myPostURL = posst["pathToImage"] as? String{
self.imageURLs.append(myPostURL)
}
}
}
}
}
}
I want my code to go through all the posts on Firebase and then check if their userID matches the currentusers uid, if they matched which means they are my images. then send the URL in pathToImage to an array in my code called imageURLs()[ "" ].but I don't know how to to that??. I am using SDWebImage to display my images to the collectionView cell. i have tested it and it works fine if i copy and paste a random URL in the array called imageURLs[ "URL here" ]
I am very new to Swift and Firebase, so any help would be greatly appreciated!! :)
HERE IS AN IMAGE OF MY FIREBASE FILES.
https://ibb.co/bXLMcb
Psst! posts/pathToImage holds the URL so that's the one i want to retrieve.
users/urlToImage is just a profile picture. i don't really need it right now
To locate specific data within a node a Query is used.
While iterating over the nodes works, if there's a million nodes it's going to take a long time and tie up the UI while waiting for that to happen.
The bottom line is; if you know what you are looking for - in this case a uid - then a query is a super simple solution.
let postsRef = self.ref.child("posts")
let query = postsRef.queryOrdered(byChild: "userID").queryEqual(toValue: "uid_0")
query.observeSingleEvent(of: .value) { (snapshot) in
if snapshot.exists() {
for child in snapshot.children { //.value can return more than 1 match
let snap = child as! DataSnapshot
let dict = snap.value as! [String: Any]
let myPostURL = dict["urlToImage"] as! String
self.imageURLs.append(myPostURL)
}
} else {
print("no user posts found")
}
}
With the above code, we first create a reference to our posts node. Then a query that will only return this users (uid_0) posts.
We then iterate over the snapshot of posts and add them to the array.
This is much more efficient that loading and evaluating every node in the database.
See Sorting And Filtering data for more information.
You should think about storing an index of all your users posts somewhere in your database. That way you don't need to observe all posts every time. This is called denormalization. Firebase has an article in their docs about organizing your database.
Here's some information regarding firebase filtering in swift.
The best solution is to add a separate node that has a list of "post IDs" organized by user. Then you could observe that node, and only download each post specifically by the returned ID. Here's a link about flattening data structures in firebase. It would look something like this.
"posts":{
"somePostID":{
"timestamp": "0200231023",
"postContent": "here's my post content",
"authorUID" : "0239480238402934"
} ...
},
"postsByGivenUID":{
"someAuthorID":{
"somePostID": "true",
"somePostID": "true",
},
"someOtherAuthorID":{
"somePostID": "true",
"somePostID": "true",
"somePostID": "true"
}
}
This is actually a much bigger problem than just changing how you structure your code. For scalability sake, you're going to have to reevaluate how you structure the data in firebase altogether.
Then, you can nest your firebase query, sort of like this:
ref.child("postByGivenUID").child("Auth.auth().currentUser?.uid").observe(.childAdded) { (snapshot) in
ref.child("posts").child(snapshot.value).observeSingleEventOfType(of: .value) { (snap) in
// your actual post data will be here
// that way you won't be downloadin ALL posts EVERY time
}
}
I am building an app that incorporates Firebase and need to be able to be able to add/and or set data at the top of the my database. Currently whenever I add data it places it randomly under the parent node. I've seen some Objective C answers to this but they haven't really made to much sense. Sorry for the lack of code, but I don't know where exactly where to start on this issue. Any help would be great!
When you say it is getting placed 'randomly' under the parent, I think this is the childByAutoId() method getting called. While the name of the nodes appears randomly (e.g. -K6tdghsbci7g8), it will actually ensure that data is added under a given parent node in order. This is very useful for adding new data to lists. For example:
let pointlessData:String = "some data"
ref.childByAutoId().setValue(pointlessData)
// creates a new ordered child node under the `ref` with "some data" as the value
There isn't really a way to order the nodes back to front in this fashion, although you could order negatively by timestamp by adding a negative timestamp to each node you add then order your results using ref.queryOrderedByChild("negativeTimestamp") such that the values you get are the newest first.
let path = FirebaseBaseUrl + "dialogs/" + self.receiverId + "/" + self.senderId
let chilRef = FIRDatabase.database().referenceFromURL(path)
let refChild = chilRef.childByAutoId()
let dic = NSMutableDictionary()
dic .setValue(text, forKey: "text")
dic .setValue(FIRServerValue.timestamp(), forKey: "timestamp")
dic .setValue(true, forKey: "your")
refChild.updateChildValues(dic as [NSObject : AnyObject]) { (error, ref) in
if(error != nil){
print("Error",error)
}else{
print("\n\n\n\n\nAdded successfully...")
}
}
How do I retrieve a value (other than username and user id, which seem easier to get) for the current user from the database.
Ironically, I can set the value as follows and that works just fine:
let databaseRef = FIRDatabase.database().reference()
userID = (FIRAuth.auth()?.currentUser?.uid)! as String
databaseRef.child("users").child(userID!).child("TermCond").setValue("Yes")
But for the life of me I cannot work out what to put instead of setValue if I simply want to retrieve the current TermCond value. I thought just using value as for example in
let DesiredValue = databaseRef.child("users").child(userID!).child("TermCond").value as? String
Would suffice, but nothing works. I am confused why retrieving the value should be more difficult than setting it.
To "read" a value from Firebase, you need to add a reference listener that gets called every time that value changes.
In your case, that could be something like:
let databaseRef = FIRDatabase.database().reference()
databaseRef.child("users").child(userID!).child("TermCond").observe(FIRDataEventType.value, with: { (snapshot) in
let desiredValue = snapshot.value as? String
})
This block of code will get triggered every time your value changes. If you only want to read it once, you can use observeSingleEvent:of:with instead of observe:with.
This is as described in the Firebase documentation: https://firebase.google.com/docs/database/ios/read-and-write
I recommend you read their entire Documentation to get an idea of how Firebase works, as it is very different from traditional databases.
I can also recommend the following tutorial if you'd like to learn a bit more about the Firebase Database and how it works: https://www.raywenderlich.com/139322/firebase-tutorial-getting-started-2
I've solved this now (based on Aleksander's reply). The way I did it is as follows.
databaseRef.child("users").child(userID!).observeSingleEvent(of: .value, with: { (snapshot) in
let value = snapshot.value as? NSDictionary
self.desiredValue = value?["TermCond"] as? String ?? ""
self.LabelToShow.text = self.desiredValue!
}) { (error) in
print(error.localizedDescription)
}
This works absolutely fine and shows the value of TermCond in the LabelToShow on my iOS screen.