swift3 : 문자열 substring 과 replace

var str = "Hello, playground"

 * 앞자리 기준

- 0번째 자리 부터 let start = str.index(str.startIndex, offsetBy: 0)  str.substring(from: start)  //Hello, playground 출력  - 2번째 자리 부터   => "offsetBy: 2"의 숫자 2는 2번째 자리가 아니라 3번째 자리이다.        index는 0부터 시작하므로, 즉 3자리미만으로 해석해야함. let end = str.index(str.startIndex, offsetBy: 2) str.substring(from: end)  //llo, playground 출력

 * 뒷자리 기준

- 뒤에서 4번째 자리 부터 let end = str.index(str.endIndex, offsetBy: -4) str.substring(from: end)  //ound 출력

 * substring

- 1번째 자리부터 2자리만 가지고 온다. let start2 = str.index(str.startIndex, offsetBy: 2) let range = start ..< start2 str.substring(with: range)  //He 출력  - 3번째 자리부터 끝에서 4번째자리 이전까지만 가지고 온다. let range2 = start ..< end str.substring(with: range2)  //llo, playgr 출력

var replaceStr = "This is my string"

 * replace

let NewString = replaceStr.replacingOccurrences(of: " ", with: "+") print(NewString) //This+is+my+string

종합하여, 해당 범위에 있는 문자를 추출하고자 한다면...

예시로 "my"를 "your"로 바꾸어 출력해 보겠다.

let begin = replaceStr.index(replaceStr.startIndex, offsetBy: 8) let finish = replaceStr.index(replaceStr.endIndex, offsetBy: -7) let NewRange = begin ..< finish let StringNew = replaceStr.replacingOccurrences(of: replaceStr.substring(with: NewRange), with: "your") print(StringNew)  //This is your string 출력

playground

//: Playground - noun: a place where people can play import UIKit let channel = "asdfg35sahadhxbadgaswgreh" let start5 = channel.index(channel.startIndex, offsetBy: 0) let end5 = channel.index(channel.startIndex, offsetBy: 2) let range5 = start5 ..< end5 channel.substring(with: range5)  // play let name5 = channel.replacingOccurrences(of: channel.substring(with: range5), with: "UU") var str = "Hello, playground" let start = str.index(str.startIndex, offsetBy: 0) str.substring(from: start) let start2 = str.index(str.startIndex, offsetBy: 2) str.substring(from: start2) let end = str.index(str.endIndex, offsetBy: -4) str.substring(from: end) let range = start ..< start2 str.substring(with: range) let range2 = start2 ..< end str.substring(with: range2) let replaceStr = "This is my string" let NewString = replaceStr.replacingOccurrences(of: " ", with: "+") print(NewString) let begin = replaceStr.index(replaceStr.startIndex, offsetBy: 8) replaceStr.substring(from: begin) let finish = replaceStr.index(replaceStr.endIndex, offsetBy: -7) replaceStr.substring(from: finish) let NewRange = begin ..< finish replaceStr.substring(with: NewRange) let name = replaceStr.replacingOccurrences(of: replaceStr.substring(with: NewRange), with: "your") print(name) let ins = "select a from name" //ins.indexes(of: " ") var rang = ins.range(of: " ") var aaa = ins.indexes(of: " ") print(aaa[1]) extension String {     func index(of string: String, options: String.CompareOptions = .literal) -> String.Index? {         return range(of: string, options: options)?.lowerBound     }     func indexes(of string: String, options: String.CompareOptions = .literal) -> [String.Index] {         var result: [String.Index] = []         var start = startIndex         while let range = range(of: string, options: options, range: start..<endIndex) {             result.append(range.lowerBound)             start = range.upperBound         }         return result     }     func ranges(of string: String, options: String.CompareOptions = .literal) -> [Range<String.Index>] {         var result: [Range<String.Index>] = []         var start = startIndex         while let range = range(of: string, options: options, range: start..<endIndex) {             result.append(range)             start = range.upperBound         }         return result     } }