How to update Firebase with struct - ios

Question

I have a struct EventDate and am trying to update a reference in Firebase.
struct EventDate {
var club: String = ""
var date: String = ""
var eventText: String = ""
var free: String = ""
var monthYear: String = ""
}
My update function throws lldb. I guess because the keys are no Strings(?)
func updateEvent(_ backendlessUserObjectID: String, event: EventDate) {
let reference = firebase.child("eventDates").child(backendlessUserObjectID).child(event.date)
reference.setValue(event) { (error, ref) -> Void in
if error != nil {
print("\(error)")
}
} // lldb here
}
If I change the function to the following, everything is fine (because Keys and Values are now Strings?)
func updateEvent(_ backendlessUserObjectID: String, event: EventDate) {
let item: NSMutableDictionary = ["club" : event.club,
"date" : event.date,
"eventText" : event.eventText,
"free" : event.free,
"monthYear" : event.monthYear]
let reference = firebase.child("eventDates").child(backendlessUserObjectID).child(event.date)
reference.setValue(item) { (error, ref) -> Void in
if error != nil {
print("\(error)")
}
}
}
Am I right that I receive lldb because the keys from my models are not Strings? Or what am I missing and how will I be able to save the values into my Firebase using my model without creating the NSMutableDictionary? Help is very appreciated.
PS: print(event.date) = 201610120200000000 -> the desired value for .child

Answer 1

Firebase data exists in a JSON format which can be thought of as key:value pairs. The keys must be strings and the values can be any of the for data types mentioned in Dravidians answer (which is a correct answer and should be accepted). I would like to add some additional comments that may help as well.
There are times when you want to use a structure in code and that can't be written to Firebase directly - you need some way to get the data out of the structure into something Firebase likes - which is a Dictionary.
Heres an example (Swift 3, Firebase 2.x)
struct EventDate {
var club: String = ""
var date: String = ""
var eventText: String = ""
var free: String = ""
var monthYear: String = ""
func getDict() -> [String:String] {
let dict = ["club": self.club,
"date": self.date,
"eventText": self.eventText,
"free": self.free,
"monthYear": self.monthYear
]
return dict
}
}
var event = EventDate()
event.club = "Wimbledon"
event.date = "20161023"
event.eventText = "Special Tennis Event"
event.free = "Free"
event.monthYear = "10/2016"
let ref = self.myRootRef.child(byAppendingPath: "events")!
let eventRef = ref.childByAutoId() //Firebase 2.x
eventRef?.setValue( event.getDict() )
This results in a node being written to Firebase that looks like this
"events" : {
"-KUli8oiM_KKw8GZ0MMm" : {
"club" : "Wimbeldon",
"date" : "20161023",
"eventText" : "Special Tennis Event",
"free" : "Free",
"monthYear" : "10/2016"
}
}

Answer 2

No it has nothing to do with the type of keys that you are trying to save in your Firebase Database its just that struct is a dataModel or to be precise a physically grouped list of variables which you initialise with some custom Data, and you can only save four types of values types in your Firebase Database:-
NSDictionary
NSArray
NSNumber
NSString
Look up the docs :- Read And Write data, Firebase- iOS
So when you cast your values in a NSMutableDictionary, you come clean of struct. And struct and class is not recognisable by the Firebase Database.