How to filter an array of structs with value of other array in swift?

Question

I have searched for this issue and I did not find any solution that is working for me using the latest version of Xcode and Swift. I use three arrays:

1. baseArray[Meal]: array filled with every meal. Not locally saved.

2. favoritesArray[Favorite]: with names of all favorite meals, locally saved by the user with NSKeyedArchiver.
3. filteredArray[Meal]: baseArray but filtered for searchterm. In code: 

    (filteredArray = baseArray.filter { $0.type == searchtext }}

I use the last array in the tableView. If they want to see all meals, the filteredArray is the same as the baseArray.

My question: how can I get the filteredArray that it has all favorite meals (so where Meal.title == Favorite.name). How do i combine three arrays?

I have tried a lot of options in the last week, but none has worked.. I hope You can help me out!!

filteredArray = baseArray.filter { $0.type == search text && favoritesArray.contains($0.type) }? (you may want to convert the favoritesArray to a Set first) — hnh
– hnh, Commented Nov 25, 2016 at 12:05

ganzogo · Accepted Answer · 2016-11-25 12:04:57Z

9

This does what you want:

struct Meal {
  let title: String
}

struct Favorite {
  let name: String
}

let meal1 = Meal(title: "Soup")
let meal2 = Meal(title: "Stew")
let meal3 = Meal(title: "Pizza")

let favorite1 = Favorite(name: "Stew")

let baseArray = [meal1, meal2, meal3]
let favoritesArray = [favorite1]

let favoriteNames = favoritesArray.map { $0.name }

let filteredArray = baseArray.filter { favoriteNames.contains($0.title) }

answered Nov 25, 2016 at 12:04

ganzogo

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2 Comments

mkw1975 Over a year ago

Thx a lot! It is working; I already had a favoritesArray so i didn't need to declare it again. The favoriteNames does the trick!

Hemang Over a year ago

Good answer, how to get the same result if let title: String? in Meal? How will you handle this here? let filteredArray = baseArray.filter { favoriteNames.contains($0.title****) } This is optional.

Lexorus · Accepted Answer · 2016-11-25 12:15:25Z

This is the solution for you if I correctly understand your question.

struct Meal {
    let name: String
}

struct Favorite {
    let name: String
}

let baseArray = [Meal(name: "Meal1"), Meal(name: "Meal2"), Meal(name: "Meal3")]

let favoritesArray = [Favorite(name: "Meal1")]

let searchText = "Meal3"

let filteredArray = baseArray.filter { $0.name == searchText }
print(filteredArray)
// [Meal(name: "Meal3")]

let combinedArray = baseArray.reduce(filteredArray) { array, element in
    // First condition check if the current meal (element) in contained in the favorites
    // Second checks if the favorite meal isn't already in the filteder array
    if favoritesArray.contains(where: { $0.name == element.name }) &&
        !filteredArray.contains(where: { $0.name == element.name }) {
        return array + [element]
    }
    return array
}

print(combinedArray)
// [Meal(name: "Meal3"), Meal(name: "Meal1")]

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