Written by Amy
on March 14, 2018

Swift String API

Swift String 다시보기

String

Swift4이후 String은 Character의 Collection이 되었다.
Swift String Cheatsheet

String은 Value 타입

var aString = "Hello"
var bString = aString
bString += " World!"    // "Hello World!"
print("\(aString)")     // "Hello\n"

repeating으로 같은 문자 반복

let hello = String(repeating:"hi", count:3) // hihihi

빈문자열

let name = ""
name.isEmpty         // true

let name = String()
name.isEmpty        // true

대소문자

let stringSample = "abcDEf"
let upper = mixedCase.uppercased() // "ABCDEF"
let lower = mixedCase.lowercased() // "abcdef"

Index

let hello = "hello"
let startIndex = hello.startIndex // 0
let endIndex = hello.endIndex     // 5 (range 밖)
hello[hello.index(after: startIndex)] // "e"
hello[hello.index(before: endIndex)]  // "o"
hello[hello.index(startIndex, offsetBy: 1)]  // "e"
hello[hello.index(endIndex, offsetBy: -4)]   // "e"

Attributed String

let font = UIFont(name: "HelveticaNeue-Light", size:20.0)!

let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.lineSpacing = 8
paragraphStyle.alignment = .center

textLabel.attributedText = NSAttributedString(string: text,
attributes: [NSAttributedStringKey.font: font, NSAttributedStringKey.paragraphStyle: paragraphStyle])

String을 Data로 Encoding/Decoding할 때 주의할 점

String to Data and Back
force-unwrapping은 위험하다. 기본적으로 리턴 타입은 Optional

URL, String

String(contentsOF:, encoding:)
String.split(seperator:)
URL.appendingPathComponent.path

let url = FileManager.default.homeDirectoryForCurrentUser.appendingPathComponent("Some Path")

let str = try! String(contentsOf: url, encoding: .ascii)

let lines = str.split(separator: "\n")

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