Accessing data inside a closure after it has been completed - swift

Question

I want to be able to access the results array, after all the data has been added from Firebase to my array. Every time I try this, I get nil array.
Objective is to have a list of location info objects in an array, loaded through Firebase.
My code snippet:
class func loadData(){
let root = FIRDatabase.database().reference()
let locationSummary = root.child("LocSummary")
locationSummary.observe(.childAdded,with: { (snapshot) in
print("inside closure")
let values = snapshot.value as? NSDictionary
let name = values?["Name"] as? String ?? ""
let rating = values?["Rating"] as? Int
let latitude = values?["Latitude"] as? Double
let longitude = values?["Longitude"] as? Double
let musicType = values?["Music"] as? String ?? ""
let loc = LocationInfo.init(name: name, rating: rating!, lat:
latitude!, long: longitude!, musicTyp: musicType)
resultsArray.append(loc)
})
}

Answer 1

Try something like this:
class func loadData(completion: #escaping (_ location: LocationInfo) -> Void) {
let root = FIRDatabase.database().reference()
let locationSummary = root.child("LocSummary")
locationSummary.observe(.childAdded,with: { (snapshot) in
print("inside closure")
let values = snapshot.value as? NSDictionary
let name = values?["Name"] as? String ?? ""
let rating = values?["Rating"] as? Int
let latitude = values?["Latitude"] as? Double
let longitude = values?["Longitude"] as? Double
let musicType = values?["Music"] as? String ?? ""
let loc = LocationInfo.init(name: name, rating: rating!, lat:
latitude!, long: longitude!, musicTyp: musicType)
completion(loc)
})
}
In your cycle add something like this:
func getArray(completion: #escaping (_ yourArray: [LocationInfo]) -> Void {
var resultsArray = [LocationInfo]()
let countOfLoadedItems = 0
for item in yourArrayForCycle { // or your own cycle. Implement your logic
loadData(completion: { location in
countOfLoadedItems += 1
resultsArray.append(location)
if countOfLoadedItems == yourArrayForCycle.count {
completion(resultsArray)
}
})
}
}
Then in function, where you wants your data:
getArray(completion: { result in
yourArrayToFill = result
// reload data etc..
})
Something like this. Adapt it to your solution.
Hope it helps