How do I save data from cloud firestore to a variable in swift?

Solution 1:

That's because Firestore function getDocument is an asynchronous function and it returns immediately and after that it continues to execute the code inside it. If you want to return a particular value from here, you need to use completion Handler. Your function may look like this.

func getDocument(path: String, field: String? = "nil", completion:@escaping(Any)->()) {
var returnVar : Any = "DEFAULT VAL"
var db: Firestore!
db = Firestore.firestore()

let docRef = db.document(path)
docRef.getDocument { (document, error) in
    if let document = document, document.exists {
        if(field != "nil"){
            let property =  document.get("phrase") ?? "nil"
            returnVar = property
            completion(returnVar)
        }
        else{
            let dataDescription = document.data().map(String.init(describing:)) ?? "nil"
            returnVar = dataDescription
            completion(returnVar)
        }
    } else {
        print("Document does not exist")
        returnVar = -1
        completion(returnVar)
      }
    }
  }

Then call the function in viewDidLoad or in any other function like this.

getDocument(path: path, field: field){(value) in
    print(value)
}

You can checkout more about Completion Handlers here