fetch duplicate in ios swift

Question

i have an array in that array there are 2000 dictionary and i want to find out the duplicates in that array.

let contacts = [
    Contact(name: "siddhant",     phone: "1234"),
    Contact(name: "nitesh", phone: "1234"),
    Contact(name: "nitin",  phone: "2222"),
    Contact(name: "himanshu",   phone: "2222"),
    Contact(name: "kedar",    phone: "3333")
]

// output should be:

[
        Contact(name: "siddhant",     phone: "1234"),
        Contact(name: "nitesh", phone: "1234"),
        Contact(name: "nitin",  phone: "2222"),
        Contact(name: "himanshu",   phone: "2222")
    ]

Here's what I've tried:-

let result = values.filter { value in values.filter({ $0.phone == value.phone }).count > 1 } 
print(result) //this takes lot time to filter 2000+ datas

let result = values.filter { value in values.filter({ $0. phone == value. phone }).count > 1 } print(result) this takes lot time to filter 2000+ datas — sid
– sid, Commented Sep 12, 2019 at 6:58
Possible duplicate of Find Duplicate Elements In Array Using Swift — Sahil Manchanda
– Sahil Manchanda, Commented Sep 12, 2019 at 7:17
I don't understand what you are asking: The line "Contact(name: "kedar", phone: "3333")" should be filtered, but how, it is not a duplicate of any other contact in your example. And I think your code is recursive (and therefore needs a lot of time) but this is not necessary. See comment from Sahil Machanda above. — LukeSideWalker
– LukeSideWalker, Commented Sep 13, 2019 at 1:24

matt · Accepted Answer · 2019-09-12 07:23:41Z

2

Group by phone number, eliminate all phone numbers that are not duplicated, and then filter the original array:

struct Contact {
    let name:String
    let phone:String
}
let contacts = [
    Contact(name: "siddhant", phone: "1234"),
    Contact(name: "nitesh", phone: "1234"),
    Contact(name: "nitin",  phone: "2222"),
    Contact(name: "himanshu", phone: "2222"),
    Contact(name: "kedar", phone: "3333")
]
let singlePhones = Set(Dictionary(grouping: contacts, by: {$0.phone}).filter{$0.1.count == 1}.map{$0.0})
let contacts2 = contacts.filter {!singlePhones.contains($0.phone)}

Result (seems to be what you asked for):

[Contact(name: "siddhant", phone: "1234"),
Contact(name: "nitesh", phone: "1234"), 
Contact(name: "nitin", phone: "2222"), 
Contact(name: "himanshu", phone: "2222")]

answered Sep 12, 2019 at 7:23

matt

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1 Comment

sid Over a year ago

thank you very much this helped me but can i know how i can get [Contact(name: "siddhant", phone: "1234"), Contact(name: "nitin", phone: "2222")]

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