Working with characters in Strings

StringsCharactersDemo.swift

var someString = "Hello there"

//Create a string using array of characters
let charArray: [Character] = ["N","I","K","E", "S", "H"]
let srtingFromArray = String(charArray) // "NIKESH"

//Get array of characters from a string
var charatctesFromString = Array(someString) // ["H", "e", "l", "l", "o", " ", "t", "h", "e", "r", "e"]
print(charatctesFromString)

//characters count in string
var numberOfCharacters = someString.count

//print all the characters in a string
for char in someString{
    print(char)
}

//H
//e
//l
//l
//o
//
//t
//h
//e
//r
//e



//Access characters at different index
var firstCharacter = someString.first
var lastCharacter = someString.last

//get character at nth index
func getCharAt(index: Int, string: String) -> Character {
    let index = string.index (string.startIndex, offsetBy: index)
    return string[index]
}

var char1 = getCharAt(index: 6, string: "Apple Inc") // I

//get substring bty specifying and start and end indices
func substring(string: String, fromIndex: Int, toIndex: Int) -> String? {
    if fromIndex < toIndex && toIndex < string.count /*use string.characters.count for swift3*/{
        let startIndex = string.index(string.startIndex, offsetBy: fromIndex)
        let endIndex = string.index(string.startIndex, offsetBy: toIndex)
        return String(string[startIndex..<endIndex])
    }else{
        return nil
    }
}

substring(string: "Hello World", fromIndex: 0, toIndex: 3)! // Hel
substring(string: "Hello World", fromIndex: 0, toIndex: 20) // nil