How to give values to a Realm List <Double>?-CodePudding

How to give values to a Realm List ? I've created a second class for Double values, but I don't know if it's okay to do that. I tried to do it like this but it gives me two errors:

Cannot find 'a' in scope

Cannot find 'b' in scope

import UIKit
import RealmSwift

class Man: Object {
    @Persisted var _id: String?
    @Persisted var date: Int64?
    @Persisted var values: List<Pressure?>
}

class Pressure: Object {
    @Persisted var a: Double?
    @Persisted var b: Double?
}

let realm = try! Realm.init()
let man = Man.init()

man._id = generateRandom(size: 20)
man.date = Date().timestamp
man.values = Pressure(value: [a: 2.47635, b: 8.82763])

CodePudding user response：

There are quite a few issues with the code in the question. First, I will rename the classes for readability. Man and man look very similar so I renamed the Man class as ManClass and Pressure to PressureClass

Here are a few things

1) Don't do this

let realm = try! Realm.init()

do this (see Configure and Open a Realm)

let realm = try! Realm()

2) there is no generateRandom function

man._id = generateRandom(size: 20)

if you want to create a "random" id, it's typically done with a UUID or preferably an ObjectID

@Persisted var asda = UUID().uuidString

@Persisted(primaryKey: true) var _id: ObjectId //YAY!

When the object is instatiated, that property is populated which eliminates the need to populate it manually. e.g. you don't need this

man._id = generateRandom(size: 20)

3) There is no timestamp function, and the .date property is Date, not a timestamp

man.date = Date()

4) When assigning values to properties, the property names have to be within quotes; "a" and "b" for example. Also, this is not appending a value to a list, so this doesn't work

man.values = Pressure(value: [a: 2.47635, b: 8.82763])

This does

man.values = PressureClass(value: ["a": 2.47635, "b": 8.82763])

you can also do this

let p = PressureClass()
p.a = 2.4
p.b = 8.8

and then

man.values.append(p) //add a single value to a `List`

OR you can update the PressureClass with a convenience init instead of dealing with this ["a": 2.47635, "b": 8.82763]

class PressureClass: Object {
    @Persisted(primaryKey: true) var _id: ObjectId
    @Persisted var a: Double?
    @Persisted var b: Double?

    convenience init(a: Double, b:Double) {
        self.init()
        self.a = a
        self.b = b
    }
}

and then go nuts adding values

let x = PressureClass(a: 2.4, b: 8.8)
let y = PressureClass(a: 1.5, b: 2.6)
let z = PressureClass(a: 9.5, b: 6.2)

man.values.append(objectsIn: [x, y, z]) //add multiple values to a `List`