//: Playground - noun: a place where people can play

import UIKit

var text = "Nikita go to school everyday. Nikita is a good boy. Nikita loves anime and hate music."

extension String {
    func replaceNikitaWith(name: String) -> String {
        return self.replacingOccurrences(of: "Nikita", with: name)
    }
}

text.replaceNikitaWith(name: "Ruslan")