Let's explore some practical examples of higher-order functions.
We can use reduce to calculate the sum of a list of numbers as follows:
let listOfNumbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] let sumOfNumbers = reduce(elements: listOfNumbers, initial: 0, combine: +) print(sumOfNumbers)
The result will be 55, as expected.
We can use reduce to calculate the product of array values as follows:
let productOfNumbers = reduce(elements: listOfNumbers, initial: 1, combine: *) print(productOfNumbers)
The result will be 3628800, as expected.
We can use flatMap to get values out of optional arrays and remove nil values:
let optionalArray: [String?] = ["First", "Second", nil, "Fourth"]
let nonOptionalArray = optionalArray.flatMap { $0 }
print(nonOptionalArray)
The result will be ["First", "Second", "Fourth"], as expected.