Swift Firebase Completion Block Infinite Loop - ios

Question

I am making an app that holds many books in firebase. I am getting a very strange problem wherein my application will infinite loop when adding a new book and keep adding the same book as fast as it can. If there would be any way that a more experienced person could take a look, I would be very grateful.
#IBAction func userHasBook(sender: AnyObject) { // Called after filling a new book form
let email = FIRAuth.auth()?.currentUser?.email!
let school = email!.substringWithRange(Range(email!.characters.indexOf("#")!.advancedBy(1) ..< email!.characters.indexOf(".")!)) // for db organization
//A few lines here that ensure that the fields are filled correctly (clutter so i didn't add them)
ref.child(school).observeEventType(.Value, withBlock: { (snapshot) in
self.bookIndex = snapshot.value!["numSelling"] as! Int
self.addSellingBook(); // we now know it is done finding the value, right?
}) { (error) in
print(error.localizedDescription)
}
}
func addSellingBook(){
let bookRef = self.ref.child(school).child("selling").child(Int(self.bookIndex).description)
let book : [NSObject : AnyObject] = ["uid": (FIRAuth.auth()?.currentUser?.uid)!,
"title": self.titleField.text!,
"authors": self.authorsField.text!,
"edition": self.editionField.text!,
"price": self.priceField.text!,
"isbn" : self.isbn] // this is the data that is added infinitely many times
bookRef.updateChildValues(book, withCompletionBlock: { (NSError, FIRDatabaseReference) in //update the book in the db
let newIndex = self.bookIndex + 1
self.ref.child(self.school).child("numSelling").setValue(newIndex, withCompletionBlock: { (NSError, FIRDatabaseReference) in // after that update the index
self.performSegueWithIdentifier("backToMain", sender: nil) // and after that go back to main
})
})
Thanks a ton and ask me if you need anything more!
EDIT: JSON BEFORE BELOW
{
"colorado" : {
"numBuying" : 0,
"numSelling" : 0,
"users" : {
"2nU0jp4ITjgQ6ElSQWc7t5qj62t1" : {
"email" : "vhegde#colorado.edu"
}
}
},
"creek" : {
"numBuying" : 0,
"numSelling" : 2,
"selling" : [ {
"authors" : "A. S. A. Harrison",
"edition" : "Only Edition",
"isbn" : "1101608064",
"price" : "5.00",
"title" : "The Silent Wife",
"uid" : "eJvdVx3J8EYZPH3mlbYLBcPDkD12"
}, {
"authors" : "Jamie McGuire",
"edition" : "Only Edition",
"isbn" : "1476712050",
"price" : "5.00",
"title" : "Beautiful Disaster",
"uid" : "eJvdVx3J8EYZPH3mlbYLBcPDkD12"
} ],
"users" : {
"eJvdVx3J8EYZPH3mlbYLBcPDkD12" : {
"email" : "vhegde#creek.edu"
}
}
}
}
Then, I add another book (index of 2) and rather it keeps adding infinite books and infinitely increments index (numSelling). I don't want to post that JSON as it is like 300 lines long.

Answer 1

figured it out, instead of using observeEventType, you have to use observeSingleEventOfType

Answer 2

Please change Your code as i have implemented in below method to set online/offline.
// MARK: - User Online/Offline
func setUserOnlineOffline(userId: String!, isOnline: Bool!) {
Let ref = FIRDatabase.database().reference().child(FIRPATH_USER_USERID_DETAILS(userId))
if isOnline == true {
ref.updateChildValues(["last_seen": "Online"])
} else {
ref.updateChildValues(["last_seen": FIRServerValue.timestamp()])
}
ref.onDisconnectUpdateChildValues(["last_seen": FIRServerValue.timestamp()])
}
//note: here you have to set string, so please replace dictionary of nsobject with string .. might be helpful to you