Find object by comparing two array

Question

I have two array, which has the same model.

I'm trying to find the object where it has the same id. I have tried this method which I can find it but how I can make it without for loop?

    for item in userList {

        let userSelection = user.list.first(where: {$0.id == item.id})
        item.approved = userSelection.approved

        print(userSelection)
    }

Are you trying to find all the items in userList that are also contained in user.list? — Igor Kulman
– Igor Kulman, Commented Sep 27, 2017 at 12:52
@CAN the code you gave posted would get only the first occurrence. please update your question and clarify — Leo Dabus
– Leo Dabus, Commented Sep 27, 2017 at 13:10

Igor Kulman · Accepted Answer · 2017-09-27 15:06:57Z

1

Try something like this

let userSelection = user.list.filter({userList.map({$0.id}).contains({$0.id})})

Explanation:

//get all the ids from one list
let ids = userList.map({$0.id})

//filter the second list by including all the users whose id is in the first list
let userSelection = user.list.filter({ids.contains({$0.id})})

edited Sep 27, 2017 at 15:06

answered Sep 27, 2017 at 13:03

Igor Kulman

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2 Comments

CAN Over a year ago

Thanks for your response but I am getting this issue: Cannot call the value of non-function type 'User'

Igor Kulman Over a year ago

I split it into 2 parts and described the general idea. Maybe you will have to make som adjustmens on your classes, the idea is important.

brigadir · Accepted Answer · 2017-09-27 13:02:45Z

0

If you don't care about performance, you can use set.intersection:

let set1:Set<UserType> = Set(userList)
let set2:Set<UserType> = Set(user.list)
let commonItems = set1.intersection(set2)// Intersection of two sets

answered Sep 27, 2017 at 13:02

brigadir

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Comments

Alain T. · Accepted Answer · 2017-09-27 17:14:17Z

0

Even if your model is not Hashable, you can use sets to perform the validation:

if Set(userList.map{$0.id}).subtracting(user.list.map{$0.id}).count == 0
{
  // all entries in userList exist in user.list
}
else
{
  // at least one entry of userList is not in user.list
}

answered Sep 27, 2017 at 17:14

Alain T.

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