[Swift Convenience Extensions] A list of handy extensions on the String, Array, and Character types.

Array+String+Character+Extensions.swift

import Foundation

extension Array where Element: Numeric {
    /// Returns a number that is sum of the elements in the sequence.
    func sum() -> Element {
        return self.reduce(0) { (res, next) -> Element in
            res + next
        }
    }
}

extension Character {
    private static let EMPTY_STRING_ASCII_VALUE = 32

    /// A Boolean value indicating whether this is an empty "" character.
    var isEmpty: Bool {
        return self.isASCII && self.asciiValue! == Character.EMPTY_STRING_ASCII_VALUE
    }
}

/// `CharacterCount` is a type alias for a tuple containing both the string to be used in the characterCount operation and the output of the characterCount operation, which is a dictionary where each key is a character and its associated value is the count of its key.
typealias CharacterCount = (string: String, count: [Character: Int])

extension String {
    /// Returns a tuple that contains the target string and the dictionary in which the keys are the characters in the string and the values are the count of those characters.
    func characterCount() -> CharacterCount {
        var tuple: CharacterCount = (string: self, count: [:])
        self.forEach { c in
            if !c.isEmpty {
                let val = tuple.count[c, default: 0]
                tuple.count[c] = val + 1
            }
        }

        return tuple
    }
}

extension Array where Element == String {
    /// Returns an Int that is the sum of all the character counts in each element.
    func totalCharacterCount() -> Int {
        return self.reduce(0) { (res, next) -> Int in
            res + next.count
        }
    }

    /// Returns an Int that is equal to the number of strings in the array.
    func wordCount() -> Int {
        return self.reduce(0) { (res, next) -> Int in
            res + next.components(separatedBy: " ").count
        }
    }

    /// Splits each string on ' ', flattens the intermediate array and returns it
    func flattenStringArray() -> [String] {
        return self.map { $0.components(separatedBy: " ") }.flatMap { $0 }
    }

    /// Returns an array of dictionaries, where each dictionary represents the counts of each character in every element.
    func characterCountForEachElement() -> [CharacterCount] {
        return self.map { $0.characterCount() }
    }
}

var names = ["Jon Snow", "Davos Seaworth", "Tyrion Lannister", "Margaery Tyrell", "Walder Frey", "Balon Greyjoy", "Arya Stark", "Petyr Baelish"]

names = names.flattenStringArray()

names.totalCharacterCount()

for (string, count) in names.characterCountForEachElement() {
    print("\(string): \(count)")
}