Remove objects that have duplicate keys - ios

Question

My code...
class Inbox {
var user = "name"
var pmsg = "label"
var match = ""
var resim = "photo"
var userID = ""
var distance = ""
var updated = ""
var isAttendingNow = ""
var isAttendingNowText = ""
init(user : String, pmsg: String, match: String, resim: String, userID : String, distance: String, updated: String, isAttendingNow: String, isAttendingNowText: String) {
self.user = user
self.pmsg = pmsg
self.match = match
self.resim = resim
self.userID = userID
self.distance = distance
self.updated = updated
self.isAttendingNow = isAttendingNow
self.isAttendingNowText = isAttendingNowText
}
}
var arrayOfRels: [Inbox] = [Inbox]()
My goal is to remove duplicate items for userID key.
How can I achieve that?

Answer 1

You could use a set to figure out which useIDs are unique:
func filteredRels(source [Inbox]) -> [Inbox] {
var keys: Set<String> = []
return source.filter {
if keys.contains($0.userID) {
return false
} else {
keys.insert($0.userID)
return true
}
}
}
(Banged out in the editor, so it might need some minor cleanup.)

Answer 2

Use Hashable
class RRR : Hashable {
var hashValue: Int = 0
static func == (lhs: RRR, rhs: RRR) -> Bool {
// in your case set only userID
return lhs.name == rhs.name && lhs.age == rhs.age
}
var name:String
var age:Int
init(name:String,age:Int) {
self.name = name
self.age = age
}
}
//
let arr = [RRR(name: "qqq", age: 12) ,RRR(name: "qqq", age: 12) , RRR(name: "hhhh", age: 12) , RRR(name: "ppppp", age: 12) ]
let set = Array(Set(arr))
print(set) // [ RRR(name: "qqq", age: 12) , RRR(name: "hhhh", age: 12) , RRR(name: "ppppp", age: 12)]

Answer 3

Checkout this:
extension Sequence where Iterator.Element: Hashable {
func uniqueOrdered() -> [Iterator.Element] {
return reduce([Iterator.Element]()) { $0.contains($1) ? $0 : $0 + [$1] }
}
}
class Inbox: Hashable {
...
...
static func == (lhs: User, rhs: User) -> Bool {
return lhs.userID == rhs.userID
}
}
arrayOfRels.uniqueOrdered()

Answer 4

You could do this in a couple of lines using a set:
var unique = Set<String>()
arrayOfRels = arrayOfRels.filter{unique.insert($0.userID).inserted}