iOS Interview Guide: Custom higher-order functions in Swift

Level: Easy, Priority: High

In your interviews, custom higher-order functions demonstrate strong Swift skills and problem-solving abilities, enabling you to write efficient and concise code. Be ready to explain the rationale behind your code during the interview.

Q1. How to create a custom higher-order function? Please explain with an example.

A custom higher-order function can take other functions as arguments or return other functions as results. You can encapsulate behavior and provide flexibility in your code with these custom higher-order functions.

The behavior and implementation of custom higher-order functions can be completely controlled by you. You can tailor these custom functions to fit your specific use cases and requirements.

Example: Filtering strings longer than 5 characters from an array of fruit names:

func customFilter<T>(_ inputArray: [T], _ condition: (T) -> Bool) -> [T] {
    var result = [T]()
    for element in inputArray {
        if condition(element) {
            result.append(element)
        }
    }
    return result
}

let words = ["apple", "banana", "orange", "grapes", "watermelon", "kiwi"]
let longWords = customFilter(words) {…