How to get Firebase collection data as dictionary in Swift-CodePudding

I want to read data from Firebase and return the output as a Dict to my ViewController. I did not manage to get the data returned in a valid way.

This is how I read the data:

  func getCollectionData()  -> Dictionary<String, String> {
        var returnValue: String = ""
        
        db.collection(user).getDocuments() { (querySnapshot, err) in
            
            if let err = err {
                print("Error getting documents: \(err)")
                returnValue = ""
            } else {
                for document in querySnapshot!.documents {
                    
                    let returnValue = document.data() as? Dictionary<String, String>
                    print (returnValue)
                }
            }
            
        }
        return returnValue
    }

Error:

Cannot convert return expression of type 'String' to return type 'Dictionary<String, String>'

Why is returnValue String again? I fiddled around a lot, but never found a solution, to return the data in a good way.

The output of print(returnValue) shows it's a dictionary

Optional(["url": "https://firebasestorage.googleapis.com:443/v0/b/.....9c5e73f", "email": "[email protected]"])

In my ViewController I want to use the data to fill a tableView:

 func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
        cell.textLabel?.text = Array(myReturnedDict.values)[indexPath.row]
        return cell
    }

EDIT:

I still get an empty Dictionary back as a returned value:

func getCollectionData()  -> Dictionary<String, String> {
        var returnValue = [String: String]()
        
        db.collection(user).getDocuments() { (querySnapshot, err) in
            
            if let err = err {
                print("Error getting documents: \(err)")
                returnValue = ["No":"data"]
            } else {
                for document in querySnapshot!.documents {
                    print (user)
                    
                    returnValue = (document.data() as? Dictionary<String, String>)!
                                   
                    //print (returnValue)

                }
            }
            
        }
        return returnValue
}

Can somebody help me?

CodePudding user response：

You created var returnValue: String = "" and use it default value "". To avoid it you need to change returnValue to type Dictionary<String, String> and set returnValue not like

let returnValue = document.data() as? Dictionary<String, String>

but

returnValue = document.data() as? Dictionary<String, String>

CodePudding user response：

func getCollectionData(callback: @escaping(Dictionary<String, String>)  -> Void {
        db.collection(user).getDocuments() { (querySnapshot, err) in
            
            if let err = err {
                print("Error getting documents: \(err)")
                callback(["No":"data"])
                return 
            } else {
                for document in querySnapshot!.documents {
                    callback((document.data() as? Dictionary<String, String>)!)
                }
            }
        }
}