In todays tutorial we’re going to build a very simple list that you can search by using the filter in an Array. The concept is really quite simple, but good to also be aware of for when you might decide to filter on the frontend of the app.

Lets begin by creating a data model that will contain a published array:

class DataModel: ObservableObject {
    @Published var items: [String] = [
        "Ford", "Vauxhall", "Ferrari", "Lamborghini", "Aston Martin", "Nissan", "Bentley"
    ]
}

The DataModel we use is a class. We conform to the ObservableObject protocol and use the @Published property wrapper. If the array of strings called items is changed, then the @Published property wrapper will notify any view that uses this ObservableObject that a change has happend. The view will then update.

A map in Swift provides a way to transform data. There are several types of map, but we’ll just look at compactMap and map today.

Both of these maps are similar in what they accomplish, that is, transform data. Often you will transform elements of a sequence into a new collection with transformed values.

To help clear this up we’ll look at some examples of when this might be useful.

Lets first look at compactMap. This method is used when you have an array that might contain nil values that you want to remove, or perhaps have data that you cannot work with. A compactMap removes the nil values leaving just the values that it can work with.

let numbers = ["1", "2", "three", "4", "five"]
let convertedNumbers = numbers.compactMap { Int($0) }