Trouble inserting struct arrays into one array

Question

So I have a struct that I am using to populate certain arrays.

    let mcdonalds = restaurant(name: "Mcdonalds")
    let burgerking = restaurant(name: "Burger King")
    let vinsetta = restaurant(name: "Vinsetta Garage")
    let chinaone = restaurant(name: "China One Buffet")
    let pandaexpress = restaurant(name: "Panda Express")
    let olivegarden = restaurant(name: "Olive Garden")
    let salvatore = restaurant(name: "Salvatorre Scallopinis")


    american = [mcdonalds, burgerking]
    burgers = [vinsetta]
    chinese = [chinaone, pandaexpress]
    italian = [olivegarden, salvatore]
    allRestaurantTypeArray = [american, burgers, chinese, italian]

unfortunately, when I attempt to combine my american,burgers,chinese, & italian arrays into the allrestaruranttypearray, I am greeted with a "cannot assigned a value of type "[[restaurant]]" to a value of type 'NSArray'".

would you be able to recommend any changes?

update:

You should name your structs starting with a capital letter

Leo Dabus
– Leo Dabus

2015-10-18 23:52:27 +00:00
Commented Oct 18, 2015 at 23:52 — Leo Dabus
– Leo Dabus, Commented Oct 18, 2015 at 23:52
would that change anything? or just better code syntax?

jonpeter
– jonpeter

2015-10-18 23:54:18 +00:00
Commented Oct 18, 2015 at 23:54 — jonpeter
– jonpeter, Commented Oct 18, 2015 at 23:54
There is no better syntax. It is a convention.

Leo Dabus
– Leo Dabus

2015-10-18 23:55:31 +00:00
Commented Oct 18, 2015 at 23:55 — Leo Dabus
– Leo Dabus, Commented Oct 18, 2015 at 23:55
[american, chinese, burgers].flatmap{$0}

Jeef
– Jeef

2015-10-19 16:39:58 +00:00
Commented Oct 19, 2015 at 16:39 — Jeef
– Jeef, Commented Oct 19, 2015 at 16:39

Jeef · Accepted Answer · 2015-10-19 16:43:11Z

1

You probably want to do a flatMap here ...

You are making an array of arrays which is what [[restaurant]] means.

flatMap will "flatten" them out.

struct Restaurant {
    var name = ""
}
let mcdonalds = Restaurant(name: "Mcdonalds")
let burgerking = Restaurant(name: "Burger King")
let vinsetta = Restaurant(name: "Vinsetta Garage")
let chinaone = Restaurant(name: "China One Buffet")
let pandaexpress = Restaurant(name: "Panda Express")
let olivegarden = Restaurant(name: "Olive Garden")
let salvatore = Restaurant(name: "Salvatorre Scallopinis")


let american = [mcdonalds, burgerking]
let burgers = [vinsetta]
let chinese = [chinaone, pandaexpress]
let italian = [olivegarden, salvatore]
let allRestaurantTypeArray = [american, burgers, chinese, italian]

let flattened = allRestaurantTypeArray.flatMap{$0}



flattened.first?.name  // "Mcdonalds"
flattened.last?.name   // "Salvatorre Scallopinis"

I've updated it to help you out even better:

You have to apply the flatmap to the array of arrays

edited Oct 19, 2015 at 16:43

answered Oct 18, 2015 at 23:36

Jeef

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8 Comments

jonpeter Over a year ago

I know flatmap works with numbers, but can i use this function to flatten arrays with struct instances or strings?

Jeef Over a year ago

@jonpeter my example is strings

Leo Dabus Over a year ago

@jonpeter look at the comment at another question of yours stackoverflow.com/a/33140261/2303865

jonpeter Over a year ago

I attempted that method but was unsuccessful. I wanted to try a different possibility, so I thought this attempt would be better. Which solution would you recommend @LeoDabus?

Leo Dabus Over a year ago

The fllatMap comment . Same as suggested by jeef

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