Passing a struct to construct an array of Structs

Question

I'm trying to create an array of structs by creating a function to fetch data from firestore and then passing the three structs fetched to an array of structs. Here is my code:

func fetchUsers() {

    var user1: User
    var user2: User
    var user3: User

    docRef = Firestore.firestore().document("users/user1")
    docRef.getDocument { (docSnapshot, error) in
        guard let docSnapshot = docSnapshot, docSnapshot.exists else { return }
        let myData = docSnapshot.data()
        let fName = myData!["name"] as? String ?? ""
        let fUsername = myData!["username"] as? String ?? ""
        let fBioText = myData!["bioText"] as? String ?? ""

        let user = User(name: fName, username: fUsername, bioText: fBioText, profileImage: #imageLiteral(resourceName: "mauricioprofileimage"))

        user1 = user
    }

    self.docRef = Firestore.firestore().document("users/user2")
        self.docRef.getDocument { (docSnapshot, error) in
        guard let docSnapshot = docSnapshot, docSnapshot.exists else { return }
        let myData = docSnapshot.data()
        let fName = myData!["name"] as? String ?? ""
        let fUsername = myData!["username"] as? String ?? ""
        let fBioText = myData!["bioText"] as? String ?? ""

        let user = User(name: fName, username: fUsername, bioText: fBioText, profileImage: #imageLiteral(resourceName: "trumpprofileimage"))

        user2 = user
    }

    self.docRef = Firestore.firestore().document("users/user1")
        self.docRef.getDocument { (docSnapshot, error) in
        guard let docSnapshot = docSnapshot, docSnapshot.exists else { return }
        let myData = docSnapshot.data()
        let fName = myData!["name"] as? String ?? ""
        let fUsername = myData!["username"] as? String ?? ""
        let fBioText = myData!["bioText"] as? String ?? ""

        let user = User(name: fName, username: fUsername, bioText: fBioText, profileImage: #imageLiteral(resourceName: "amandaprofileimage"))

        user3 = user
    }

    return [user1, user2, user3]
}

let users: [User] = fetchUsers()

The problem I'm getting is that when I try to fill my users array, it says that it doesn't recognize the user1, user2 and user3 that I created in the Fetchfuncion.

Ps: I'm using firestore. Thank you for all the help!

What's the actual question here?

sbarow
– sbarow

2018-01-26 21:26:41 +00:00
Commented Jan 26, 2018 at 21:26 — sbarow
– sbarow, Commented Jan 26, 2018 at 21:26
I don't understand what the question is, either.

El Tomato
– El Tomato

2018-01-26 23:50:35 +00:00
Commented Jan 26, 2018 at 23:50 — El Tomato
– El Tomato, Commented Jan 26, 2018 at 23:50
I edited the question in the end

Mauricio Takashi Kiyama
– Mauricio Takashi Kiyama

2018-01-27 02:55:47 +00:00
Commented Jan 27, 2018 at 2:55 — Mauricio Takashi Kiyama
– Mauricio Takashi Kiyama, Commented Jan 27, 2018 at 2:55

Jay · Accepted Answer · 2018-01-26 21:35:31Z

1

Put each request in a group, and only once all three users have been retrieved, return the array of users. What's happening with your code is that it's returning an array of empty users (or perhaps 1-3 inconsistently), due to the fact that these calls are asynchronous so the data returned from a firebase request isn't guaranteed to exist when the array is returned.

let group = DispatchGroup()

group.enter()
make_async_request_1 {
    // Process response
    group.leave()
}

group.enter()
make_async_request_2 {
    // Process response
    group.leave()
}

group.enter()
make_async_request_3 {
    // Process response
    group.leave()
}
group.notify(queue: .main) {
    // This will run after all 3 group.leave() calls are made
}

answered Jan 26, 2018 at 21:35

Jay

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4 Comments

J. Doe Over a year ago

@MauricioTakashiKiyama its for anything that is asynchronous, I use this a lot :)

Mauricio Takashi Kiyama Over a year ago

@Jay make_async_request_1 is getting the errors "Use of unresolved identifier "make_async_request_1" and 2 and 3 as well.

Jay Over a year ago

@MauricioTakashiKiyama that's because those are placeholders, they aren't literal swift code. Those would be the functions you want to execute asynchronously.

Jay Over a year ago

@MauricioTakashiKiyama did the answer work? If so please mark my answer as correct

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