Loop through multiple lists - swift

Question

I have three dictionaries structured as [Int : Int]. Each dictionary is associated with an object. The key of the dictionary is a value of the object, and the value of the dictionary is how many object of that key should exist. One object holds all of these objects. So it would look at little like this.
class Cart {
var fruit: Fruit?
var cereal: Cereal?
var juice: Juice?
}
class Food {
var key: Int?
var text: String?
}
class Fruit: Food ...
class Cereal: Food ...
class Juice: Food ...
The idea is that the user has entered values for each possible option in text boxes and then a dictionary for each object is made. I need to make carts for every object, and each cart needs to holdas many objects as it can. If I have 6 fruits, 5 cereals, and 6 juices, then there should be 6 carts, one of them missing a cereal.
I have everything working up to figuring out how to actually put them together. Here's my loop.
for (key, value) in fruitValues {
for _ in 0..<value {
print(realm.objects(Fruit.self).filter("value == \(key)"))
}
}
How can I best loop through one array and get values from the others?

Answer 1

Here is my attempt to solve this, not the most compact solution but I couldn't figure out anything shorter. Assume our 3 dictionaries from the users selection
let dictFruit = [1: 2, 2: 4]
let dictCereal = [3: 5]
let dictJuice = [4: 3, 5:2, 6: 1]
for this example I use a dictionary as my Food types storage
let products = [1: Fruit(key: 1), 2: Fruit(key: 2), 3: Cereal(key: 3), 4:Juice(key: 4), 5:Juice(key: 5), 6:Juice(key: 6)]
First step is to flatten out the dictionaries to arrays of Food objects which is done with this function
func expandSelected<T: Food>(from dict: [Int: Int]) -> [T] {
return dict.reduce(into: []) {
if let food = products[$1.key] as? T {
$0.append(contentsOf: Array(repeating: food, count: $1.value))
}
}
}
Which I then used
let fruits: [Fruit] = expandSelected(from: dictFruit)
let juices: [Juice] = expandSelected(from: dictJuice)
let cereals: [Cereal] = expandSelected(from: dictCereal)
then for the last part I used an old fashioned for loop to create the Cart items
var carts = [Cart]()
for i in 0..<max(fruits.count, juices.count, cereals.count) {
let cart = Cart()
cart.cereal = cereals.count > i ? cereals[i] : nil
cart.fruit = fruits.count > i ? fruits[i] : nil
cart.juice = juices.count > i ? juices[i] : nil
carts.append(cart)
}