How to iterate through array of objects in Swift?

Question

i have objects

var person1 = Person()
person1.name = "Joe"
person1.lastName = "Doe"
person1.age = 21

var person2 = Person()
person2.name = "Julia"
person2.lastName = "Ivanova"
person2.age = 22

var person3 = Person()
person3.name = "Irina"
person3.lastName = "Petrova"
person3.age = 25

var person9 = Person()
person9.name = "Vova"
person9.lastName = "Vovin"
person9.age = 32

var person10 = Person()
person10.name = "Masha"
person10.lastName = "Golovanova"
person10.age = 20

var person11 = Person()
person11.name = "Petra"
person11.lastName = "Andreeva"
person11.age = 27

and multi array

var array = [[person1, person2, person3], [person9, person10, person11]]

how can I iterate through array to get for example a person with name="Masha"

thanks in advance

Possible duplicate of How to loop through an array of objects in swift — Cœur
– Cœur, Commented Nov 29, 2016 at 4:03

Rachel Harvey · Accepted Answer · 2015-09-17 20:21:15Z

67

I would try this:

var array:[[Person]] = [[person1, person2, person3], [person9, person10, person11]]
/*Casting it like this should keep from getting an error later 
   and/or having to recast the objects*/

for people in array {

/*This is going to look at each array in arrays, 
   and call each one 'people' within this loop*/

    for person in people {

    /*Same thing, this is going to look at each item in the people array
       and call each one 'person' within this loop*/

        if person.name == "Masha" {
            return person
        }
    }
}

edited Sep 17, 2015 at 20:21

answered Jul 27, 2015 at 11:57

Rachel Harvey

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1 Comment

Lakshmi Yadav Over a year ago

what if I have "N" times nested array. Then?

Fantattitude · Accepted Answer · 2015-07-27 12:10:59Z

21

An interesting way of solving this would be to leverage the flatMap function of Swift.

var array = [[person1, person2, person3], [person9, person10, person11]]

let flatArray = array.flatMap { $0 }

flatArray now is [person1, person2, person3, person9, person10, person11] of type Array<Person>.

Then you can iterate on flatArray to find what you want :

for person in flatArray {
    if person.name == "Masha" {
        // Do something
    }
}

You could even go further by using Swift 2.0 because it allows you to put a where clause in the for :

for person in flatArray where person.name == "Masha" {
    // Do something
}

answered Jul 27, 2015 at 12:10

Fantattitude

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Comments

Alexey Bondarchuk · Accepted Answer · 2017-05-09 12:10:05Z

19

Here is technique which called 'Chaining'

Playground. Swift 3.1

import UIKit

class Person {
    var name = ""
    var lastName = ""
    var age = 0
}

var person1 = Person()
person1.name = "Joe"
person1.lastName = "Doe"
person1.age = 21

var person2 = Person()
person2.name = "Julia"
person2.lastName = "Ivanova"
person2.age = 22

var person3 = Person()
person3.name = "Irina"
person3.lastName = "Petrova"
person3.age = 25

var person9 = Person()
person9.name = "Vova"
person9.lastName = "Vovin"
person9.age = 32

var person10 = Person()
person10.name = "Masha"
person10.lastName = "Golovanova"
person10.age = 20

var person11 = Person()
person11.name = "Petra"
person11.lastName = "Andreeva"
person11.age = 27

var array = [[person1, person2, person3], [person9, person10, person11]]

array
    .flatMap{$0}
    .forEach { (anyPerson:Person) in

        if anyPerson.name == "Masha" {
            //Do what you need
            print(anyPerson.lastName)
        }
}

Screen-shot from playground:

edited May 9, 2017 at 12:10

answered Aug 12, 2015 at 16:22

Alexey Bondarchuk

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3 Comments

LiweiZ Over a year ago

A quick google did not come up with official document on forEach. I did find some blogs mentioned writing an extension to add forEach to Array. Could you point some documents on forEach? Thanks in advance.

Alexey Bondarchuk Over a year ago

@LiweiZ 1. Array conforms to 'SequenceType' protocol. Documentation: link 2. In playground or Xcode -> Hold 'cmd' + hover mouse to the .forEach method and do mouse click.

LiweiZ Over a year ago

@ AlexeyBondarchuk Thanks for your reply. Upvoted both your answer and comment.

Antonio · Accepted Answer · 2015-07-27 12:09:29Z

10

Iterating can be done as in @Rachel's answer. However there are different ways of doing the same thing, and not necessarily by iterating - and in some cases with just one line of code.

If you want to find, then the best way is using the array's filter method - but before that the multi dimensional array should be flattened, using flatMap.

So, to find the first element having a certain name, you can simply do:

let result: Person? = array.flatMap { $0 }.filter { $0.name == "Masha" }.first

answered Jul 27, 2015 at 12:09

Antonio

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3 Comments

Alexey K Over a year ago

Thanks! I have never meet construction { $0 } before. What to ask Google about to find out ?

Fantattitude Over a year ago

@AlexeyK Search for Shorthand Argument Names in developer.apple.com/library/ios/documentation/Swift/Conceptual/…

Antonio Over a year ago

That's a closure syntax simplification - it's a trailing closure using parameters type inference, shorthand argument names and implicit return. Read Closure Expressions

pkamb · Accepted Answer · 2019-11-15 23:04:32Z

9

Swift 3:

forEach({ element in
  // do what you need
})

edited Nov 15, 2019 at 23:04

pkamb

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answered Feb 28, 2017 at 14:34

Amjad Tubasi

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1 Comment

mmmmmm Over a year ago

That gets vectors of Persons so need another for loop

nslllava · Accepted Answer · 2018-12-03 00:29:11Z

3

Here is a pretty simple way to do what you need:

let result = array
    .flatMap { $0 }
    .first(where: { $0.name == "Masha" })

First you have to make your array flatted and then you can just get the first element from the array that satisfies the given predicate (in our case, where name is equal to "Masha").

answered Dec 3, 2018 at 0:29

nslllava

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