String+CoreFoundation.swift

import Foundation

public extension String {

    var length: Int { return count }
    var isPresent: Bool { return !isEmpty }
    var digits: String {
        return components(separatedBy: CharacterSet.decimalDigits.inverted)
            .joined()
    }

    func replace(_ string: String, with withString: String) -> String {
        return replacingOccurrences(of: string, with: withString)
    }

    func truncate(_ length: Int, suffix: String = "...") -> String {
        return self.length > length
            ? substring(to: characters.index(startIndex, offsetBy: length)) + suffix
            : self
    }

    func split(_ delimiter: String) -> [String] {
        let components = self.components(separatedBy: delimiter)
        return components != [""] ? components : []
    }

    func trim() -> String {
        return trimmingCharacters(in: CharacterSet.whitespaces)
    }

    var uppercaseFirstLetter: String {
        guard isPresent else { return self }

        var string = self
        string.replaceSubrange(string.startIndex...string.startIndex,
                               with: String(string[string.startIndex]).capitalized)
        return string
    }
}