ios - 在对象数组上循环并显示项目而不重复它们

Question

我有一个包含地区和城市的对象数组..这些地区和城市可以在多个对象中重复..

我想循环显示这些地区和城市而不重复它们......

我该怎么做？

这是类(class):

  struct Shifts : Decodable{
let id: Int
let region: String
let city: String
let nationality: String
let idService: Int
let shiftDate: String
let shiftType: String
let weekday: String
let quantityStaff: Int
let leadHours: Int
let createdAt: String?
let updatedAt: String?
let deletedAt: String?
}

数组示例:

shift=[(id: 1, region: Eastern, city: Dammam, nationality: Saudi, idService: 1, shiftDate: 11-12-2019, shiftType: day, weekday: sat, quantityStaff: 1, leadHours: 7),(id:2, region: eastern, city: dhahran, nationality: saudi, idService: 2, shiftDate: 22-1-12018, shiftType: full, weekday: mon, quantityStaff: 2, leadHours: 4)]

两个类次都在东部地区..所以我不想为用户显示东部两次...

我会将它们显示在表格 View 中作为下拉列表，以便用户可以从中进行选择..并且我不想为他们重复它..我只想显示一次。

Answer 1

struct Shifts : Decodable{
    let id: Int
    let region: String
    let city: String
    let nationality: String
    let idService: Int
    let shiftDate: String
    let shiftType: String
    let weekday: String
    let quantityStaff: Int
    let leadHours: Int
    let createdAt: String?
    let updatedAt: String?
    let deletedAt: String?
}

struct Area: Hashable{
    var region : String
    var city : String

    var hashValue: Int {
        return "(\(region),\(city))".hashValue
    }

    static func == (lhs: Area, rhs: Area) -> Bool {
        return lhs.region == rhs.region && lhs.city == rhs.city
    }
}

let shiftsArr = [Shifts]()

var seen = Set<Area>()
var unique = [Shifts]()
for shift in shiftsArr {
    let area = Area(region: shift.region, city:shift.city)
    if !seen.contains(area) {
        unique.append(shift)
        seen.insert(area)
    }
}

let areas = unique.map{
    return Area(region: $0.region, city: $0.city)
}