Find index of objects array

Question

I can't figure out how to find index of object in array. For example I have this data structure:

class Person {
var name: String
var age: Int

init(name personName: String, age personAge: Int) {
    self.name = personName
    self.age = personAge
  }
}

let person1 = Person(name: "person1", age: 34)
let person2 = Person(name: "person2", age: 30)
...
var personsArray = [person1, person2, ...]

I tried to use personsArray.index(where: ....) but I don't understand how to use it. index(of: ...) doesn't work. I think because personsArray doesn't conform to Equatable protocol...

Use http://stackoverflow.com/a/32923407/1187415 if you want to find the identical object. — Martin R, Apr 26 '17 at 08:15

score 27 · Accepted Answer · edited Apr 26 '17 at 08:25

27

index(of: )

gets the Person in your case - it is generic function.

index(where: )

gets the condition for which you want to find particular Person

What you could do:

personsArray.index(where: { $0.name == "person1" })

Or you could send object to:

personsArray.index(of: existingPerson)

For both options you could get nil - you will have to check it for nil (or guard it).

edited Apr 26 '17 at 08:25

Ozgur Vatansever

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answered Apr 26 '17 at 08:07

Miknash

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`index(of: )` doen't compile ( . Thanks for sharing, I will use `(where: $0.name == ...)` – Alex_slayer Apr 26 '17 at 08:12
Don't forget {} for where and for index(of: ) You need to provide actual object of the array – Miknash Apr 26 '17 at 08:16

score 5 · Answer 2 · answered Apr 26 '17 at 08:21

5

From my point of view just compare with ===.

Small example.

func getPersonIndex(from: [Person], user: Person) -> Int? {
    return from.index(where: { $0 === user })
}

getPersonIndex(from: personsArray, user: person2)

answered Apr 26 '17 at 08:21

Oleg Gordiichuk

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score 0 · Answer 3 · answered Apr 26 '17 at 08:07

0

I found how to use .index(where...

personsArray.index { (item) -> Bool in item.name == "person2" && item.age == 30 }

answered Apr 26 '17 at 08:07

Alex_slayer

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Find index of objects array

3 Answers3