How do i return the value of an Array from snapshot closure and use it in prepare for segue? - swift

Question

I'm trying to get the value of an Array outside the function.But as soon as the block for the snapshot ends the value of newArray gets empty.
I want to access the value of an Array even after the closure ends.
After passing the value from prepare for segue to the next View Controller the value is still empty.
var newArray = [Any]()
func getData(refe: String) -> [Any]{
let currUser = Auth.auth().currentUser?.uid
let ref = Database.database().reference(fromURL: "MyURL").child("users/\(currUser!)/Questions/")
ref.child("\(refe)").observeSingleEvent(of: .childAdded, with:{ snapshot in
let enumerator = snapshot.children
while let rest = enumerator.nextObject() as? DataSnapshot, let value = rest.value{
self.newArray.append(value as! Any)
}
print(self.newArray)
//This gives [test,test1,test2]
})
return newArray
// Here the Array is empty.
}
Actual Result: []
Expected Result: [test, test1, test2]
I also tried this.
func getData(refe: String, completion: #escaping (([Any]) -> ())) {
var newArray = [Any]()
let currUser = Auth.auth().currentUser?.uid
let ref = Database.database().reference(fromURL: "MYURL").child("users/\(currUser!)/Questions/")
ref.child("\(refe)").observeSingleEvent(of: .childAdded, with: { snapshot in
let enumerator = snapshot.children
while let rest = enumerator.nextObject() as? DataSnapshot, let value = rest.value{
newArray.append(value)
}
completion(newArray)
})
}
and calling it in helper function
func getDataD() -> [Any]{
let ref = getReference()
var arr = [Any]()
self.getData(refe: ref) { (array) in
arr = array
// This gives [test,test1,test2]
}
return arr
// This gives []
}
After that calling the function in prepare for segue
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
guard let detailViewController = segue.destination as? HostOptionTableViewController
else {
return
}
detailViewController.ref = getReference()
self.getData(refe: detailViewController.ref) { (array) in
detailViewController.data = array
}
}
}
Actual result of detailViewController.data after execution should be [test,test1,test2]
but it is []

Answer 1

It's too late to call getData inside prepareForSegue , This should be inside the action that navigates to the second vc
self.getData(refe:yourRef) { array in
self.performSegue(withIdentifier:"segueName",sender:array)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
guard let detailViewController = segue.destination as? HostOptionTableViewController
else {
return
}
detailViewController.ref = getReference()
detailViewController.data = sender as! [Model] // Model is type of array
}
the request is asynchronous and the navigation will occur before getting the data