save arrays of json in firebase with my swift 4 app - ios

Question

I have an app that shows 4 options. Everyday you click on one or more of the options. Right now, it's storing in the firebase database like an array of string, where every string is one of the options. Like this
override func addSelection(selection: String) {
self.quitPlan.medications.append(selection)
}
var medications: [String] {
get {
return document[Properties.medications.rawValue] as? [String] ?? []
}
set {
document[Properties.medications.rawValue] = newValue
}
}
But I actually want an array of jsons, with the option and the option. I have try:
override func addSelection(selection: String) {
let medicationSelected = Medication(medication: selection, date: Date())
self.quitPlan.medications.append(medicationSelected)
}
var medications: [Medication] {
get {
return document[Properties.medications.rawValue] as? [Medication] ?? []
}
set {
document[Properties.medications.rawValue] = newValue
}
}
struct Medication {
let medication: String
let date: Date
}
But it's not working, I'm getting 'FIRInvalidArgumentException', reason: 'Unsupported type: __SwiftValue'

Answer 1

You can do something like this:
struct Medication {
let medication: String
let date: Date
private let divider = "|"
func toString() -> String {
return midication + divider + date.toString()
}
func from(_ string: String) -> Medication {
let arr = string.split(divider)
let medication = arr[0]
let date = // TODO: Date from string arr[1]
return Medication(medication: medication, date: date)
}}
and
self.quitPlan.medications.append(medicationSelected.toString())

Answer 2

Firebase cannot save custom Swift structs.
A possible solution is to encode the array of Medication to a JSON string.
struct Medication : Codable {
let medication: String
let date: Date
}
In the database change the type from an array of string to single string
var medications: [Medication] {
get {
guard let medicationJSON = document[Properties.medications.rawValue] as? String,
let data = medicationJSON.data(using: .utf8),
let medi = try? JSONDecoder().decode([Medication].self, from: data) else { return [] }
return medi
}
set {
let medicationData = try! JSONEncoder().encode(newValue)
document[Properties.medications.rawValue] = String(data: medicationData, encoding: .utf8)!
}
}

Answer 3

Firestore can save a Swift struct to a collection, there is a module for this.
First, you should include the module:
import FirebaseFirestoreSwift
Then, just do:
db.collection("yourCollectionName").document(from: yourSwiftObject)
It will be converted to be saved in your Firestore collection.