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

Solution 1

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
        }
    }
}

Solution 2

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
}

Solution 3

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:

Solution 4

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

Solution 5

Swift 3:

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

View more solutions

Comments

[Alexey K]

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

[Fantattitude]

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

[Antonio]

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

[LiweiZ]

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]

@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]

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

[mmmmmm]

That gets vectors of Persons so need another for loop

[Lakshmi Yadav]

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