The power of map in Swift

The map function in Swift is a powerful tool for transforming the elements of a collection in a concise and expressive way. It allows you to apply a specific operation to each element of a collection, such as converting an array of integers to an array of strings, or doubling the values in an array of numbers.

The map function takes one argument, a closure that specifies the transformation to be applied to each element of the collection. The closure takes one argument, the current element being processed, and returns a new value, which becomes the corresponding element in the new collection.

For example, if you have an array of integers and you want to double the values in the array, you could use the map function like this:

let numbers = [1, 2, 3, 4, 5]
let doubledNumbers = numbers.map { $0 * 2 }
print(doubledNumbers) // prints [2, 4, 6, 8, 10]

In this case, the closure is { $0 * 2 }, which takes a single argument, an integer, and returns its double. The map function applies this closure to each element of the numbers array, creating a new array that contains the doubled values.

Another example, we could use the map function to convert an array of integers to an array of strings, like this:

let numbers = [1, 2, 3, 4, 5]
let strings = numbers.map { String($0) }
print(strings) // prints ["1", "2", "3", "4", "5"]

In this example, the closure is { String($0) }, which takes a single argument, an integer, and returns its string representation. The map function applies this closure to each element of the numbers array, creating a new array that contains the string representations of the integers.

We can also use map function to transform array of custom objects to new custom objects, let’s say we have a custom object Person and we want to create an array of Person ages.

struct Person {
    let name: String
    let age: Int
}
let people = [Person(name: "John", age: 30), Person(name: "Jessica", age: 25)]
let ages = people.map { $0.age }
print(ages) // prints [30, 25]

The map function is a powerful tool for transforming collections in a concise and expressive way. It allows you to apply a specific operation to each element of a collection and create a new collection with the results, without the need for explicit loops or mutable variables. This makes it an excellent choice for functional programming, and for situations where you need to perform a simple, one-time transformation of a collection.

✍️ Written by Ishtiak Ahmed

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