observerSingleEvent function not being ran with Firebase - swift

Question

I'm trying to run a function to be able to retrieve data from the realtime database with Firebase, however whenever I run the function; the observerSingleEvent part of my function will not run, I have tried putting a print statement within and it is not being run nor is the fields being read to the variable, any help would be beneficial.
func checkIfNewDay() -> Bool {
print(self.currDate)
var ref: FIRDatabaseReference!
ref = FIRDatabase.database().reference()
let userID = FIRAuth.auth()?.currentUser?.uid
print("outside function")
ref.child("user").child(userID!).child("dates").observeSingleEvent(of: .value, with: { (snapshot) in
// Get user value
print("inside function")
let value = snapshot.value as? NSDictionary
print("just to make sure its going inside the function. Delete after")
self.lastDate = value?["lastSaveDate"] as? String ?? "Date Invalid"
self.newLastDate = String(self.lastDate)
if self.newLastDate != "Date Invalid" {
print(self.lastDate)
} else {
print("Error, date not able to be recieved from the database")
self.catchGetDateError = true
self.saveCurrentDate()
}
})
if (!self.catchGetDateError) {
print(self.newLastDate, "newLastDate")
print(self.currentDate, "currentDate")
if (self.newLastDate == self.currentDate) {
print("Day has not moved on.")
return false
} else {
print("Day has moved on!")
return true
}
}
return true
}
I apologise for the really long function - was quite a weird one to write.

Answer 1

From comments I think I have understood, what do you want.
For getting this results like sync, you need to implement escaping. Like this:
func checkIfNewDay(completion: #escaping (_ isNew: Bool) -> Void) {
print(self.currDate)
var ref: FIRDatabaseReference!
ref = FIRDatabase.database().reference()
let userID = FIRAuth.auth()?.currentUser?.uid
print("outside function")
ref.child("user").child(userID!).child("dates").observeSingleEvent(of: .value, with: { (snapshot) in
// Get user value
print("inside function")
let value = snapshot.value as? NSDictionary
print("just to make sure its going inside the function. Delete after")
self.lastDate = value?["lastSaveDate"] as? String ?? "Date Invalid"
self.newLastDate = String(self.lastDate)
if self.newLastDate != "Date Invalid" {
print(self.lastDate)
if (self.newLastDate == self.currentDate) {
print("Day has not moved on.")
completion(false)
} else {
print("Day has moved on!")
completion(true)
}
} else {
print("Error, date not able to be recieved from the database")
self.catchGetDateError = true
self.saveCurrentDate()
completion(false)
}
})
}
So, now you can use your func:
checkIfNewDay(completion: { isNew in
// do whatever you want. isNew will have info, that you need.
})
You should have it, because .observe functions work async. You should understand the idea.
Hope it helps.