Filter array of nested structs - swift

Question

I'm looking for a nice swift solution for the following problem:
Lets say we have 2 structs like so:
struct Person {
let name: String
let age: Int
let skills: Skills
init(name: String, age: Int, skills: Skills) {
self.name = name
self.age = age
self.skills = skills
}
}
struct Skills {
let canUseBow: Bool
let canUseSword: Bool
let canUseShield: Bool
init(canUseBow: Bool, canUseSword: Bool, canUseShield: Bool) {
self.canUseBow = canUseBow
self.canUseSword = canUseSword
self.canUseShield = canUseShield
}
}
Now lets say I have an array of Person where each person has their own skills obviously where the corrosponding values can be true or false.
Lets say I want another array of just people that have the skill canUseBow as true so that skill must be set to true , how would I go about filtering out the Persons that do not have canUseBow set to true?
I was thinking in a direction of:
filteredPersons = persons.filter {
$0.skills
}
But that way it would require me to than select something after skills for example
$0.skills.canUseBow
That does not seem very future proof, lets say I would want to add more skills than I would also have to change the filter method again. Are there better ways to go about this?

Answer 1

You can try this with an OptionSet that can hold all of these flags for you in a simple Int storage.
import Foundation
struct Person {
let name: String
let age: Int
let skills: Skills
init(name: String, age: Int, skills: Skills) {
self.name = name
self.age = age
self.skills = skills
}
}
struct Skills: OptionSet {
let rawValue: Int
init(rawValue: Int) {
self.rawValue = rawValue
}
static let canUseBow = Skills(rawValue: 1 << 0)
static let canUseSword = Skills(rawValue: 1 << 1)
static let canUseShield = Skills(rawValue: 1 << 2)
init(json: [String: Bool]) {
var skills = Skills(rawValue: 0)
if let canUseBow = json["can_use_bow"], canUseBow {
skills.insert(.canUseBow)
}
if let canUseSword = json["can_use_sword"], canUseSword {
skills.insert(.canUseSword)
}
if let canUseShield = json["can_use_shield"], canUseShield {
skills.insert(.canUseShield)
}
self = skills
}
}
How to instantiate Skills?
let skills = Skills(json: [
"can_use_bow" : true,
"can_use_sword" : true,
"can_use_shield" : false,
])
How to filter based on multiple skills?
let targetSkills: Skills = [.canUseBow, .canUseSword]
let persons: [Person] = []
let filteredPersons = persons.filter {
targetSkills.isSubset(of: $0.skills)
}